TY - JOUR
AU - Pauli, Jonathan, N
AB - Abstract While polygyny is the dominant mating system in mammals, it is increasingly recognized that promiscuity occurs in most species. Using a long-term genetic and space-use data set, we documented the mating system for 2 sedentary and uniparous species of tree sloths, brown-throated three-toed (Bradypus variegatus) and Hoffmann’s two-toed (Choloepus hoffmanni) sloths. We predicted that the life history of these species facilitates female strategies that promote mating with multiple males across breeding seasons, and shape central features of the mating system in tree sloths. We found that many female sloths mated with different males during our study: 70% of female B. variegatus and 50% of female C. hoffmanni switched mates among years at least once during our study. Our observations of individual movements suggested that females employed 2 strategies that appeared to influence mate switching across breeding seasons: 1) selecting a male from a pool of males in their activity center, and 2) mating with different males by shifting their home ranges during estrus. Collectively, our findings suggest that individual variation in female reproductive strategies contributes to shaping the mating systems for a sedentary mammal like sloths, and highlights the need for long-term studies to effectively capture the mating systems of mammals with slow life histories. Aunque la poligamia es el sistema de apareamiento dominante en los mamíferos, es cada vez más reconocido que las hembras en la mayoría de las especies de mamíferos se aparean con múltiples machos. Usando un set de datos genéticos y de uso de hábitat a largo plazo, se documentó el sistema de apareamiento de dos especies sedentarias y uníparas, el perezoso grisáceo (Bradypus variegatus) y el perico ligero (Choloepus hoffmanni). Se predijo que las características de estas especies, facilitan que las hembras presenten estrategias que promuevan el apareamiento con múltiples machos, determinando finalmente el sistema de apareamiento en estas especies. Se encontró que muchas hembras se aparearon con múltiples machos: 70% de las hembras de B. variegatus y el 50% de las de C. hoffmanni presentaron múltiples parejas por lo menos una vez durante esta investigación. Nuestras observaciones sobre movimientos individuales revelaron que las hembras cambian de pareja bajo diferentes escenarios: (1) apareamiento con machos diferentes en cada estro, de los que se superponen en su ámbito hogareño (2), apareamiento con machos diferentes al cambiar su ámbito hogareño durante el estro. Estas evidencias sugieren que las estrategias reproductivas individuales de las hembras ayudan a modelar el sistema reproductivo de especies sedentarias como los perezosos; finalmente, es importante destacar la necesidad de investigaciones a largo plazo para poder entender los sistemas de apareamiento de especies con lenta historia de vida. female choice, parentage inference, reproductive skew, sloth Mammalian mating systems exist along a spectrum, ranging from monogamy to those featuring essentially no mate bonding (Clutton-Brock 1989; Shuster and Wade 2003). As such, mating strategies are typically classified based on the number of partners with whom individuals mate and the level of paternal care (e.g., Emlen and Oring 1977; Reynolds 1996). Interspecific and intraspecific variation in mating systems can be influenced by the spatial and temporal distribution of resources, population density, and mate choice (Emlen and Oring 1977; Kamler et al. 2004; Martin and Martin 2007). Mating systems are, however, broad generalizations of reproductive strategies at the species or population level and individuals can exhibit significant variation in reproductive behavior in an attempt to enhance reproductive fitness (Emlen and Oring 1977; Lott 1991; Fisher and Lara 1999; Jennions and Petrie 2000). Polygyny, where males monopolize multiple females, is considered the dominant mating system among mammals as it occurs in approximately 90% of species (Rutberg 1983; Clutton-Brock 1989). With the advent of molecular methods, it is increasingly apparent, however, that promiscuity is common in putatively strongly polygynous taxa (McEachern et al. 2009; Beasley et al. 2010). From the female’s perspective, mating with multiple males can increase genetic diversity in offspring and reduce the risk of infanticide (Eizaguirre et al. 2007; Kekäläinen et al. 2010; Gowaty 2013). In some cases, multiple paternity can be explained by forced copulations (Wolff and Macdonald 2004), or by sperm competition (Parker 1970; Soulsbury 2010) among males, but for species where such aggression is absent or male testes sizes are small, multiple paternity appears to be principally the result of mate switching (Clutton-Brock and McAuliffe 2009). Most research into mammalian mating systems has been conducted in species where mate guarding is present (although see Crichton and Krutzsch 2000; Boness et al. 2006). In such species, mating systems are characterized by strong polygyny, high male reproductive skew, and low mate switching (e.g., Clutton-Brock 1998; Allainé 2000; Martin et al. 2007). For species without mate guarding, mating systems appear to be more flexible, with females playing a greater role in structuring features of mating systems such as reproductive skew among males (Fisher and Lara 1999; Jennions and Petrie 2000; Garnier et al. 2001; Beasley et al. 2010). Tree sloths are the dominant vertebrate herbivore of Neotropical forests (Montgomery and Sunquist 1975), with extremely low metabolic rates and energetic budgets (Pauli et al. 2016). Their sedentary and solitary nature precludes mate guarding and their small testes size (Britton 1941) suggests that sperm competition is not a predominant feature (Kenagy and Trombulak 1986), all of which points to the reproductive strategy of females as being potentially important in shaping mating systems in this taxon (Taube et al. 2001; Vaughan et al. 2007). Based on limited sample sizes, we have previously shown that brown-throated three-toed sloths (Bradypus variegatus) are strongly polygynous, males exhibit strong reproductive skew, and a female mating with multiple males is relatively infrequent (Pauli and Peery 2012). In contrast, Hoffmann’s two-toed sloths (Choloepus hoffmanni) exhibit a mixture of polygyny and promiscuity (Peery and Pauli 2012). However, assessing the mating system for species such as tree sloths, where females produce a single offspring per reproductive cycle, is challenging given the need to observe the outcome of multiple breeding events (Garnier et al. 2001). Thus, these relatively short-term studies are insufficient to fully assess central features of a mating system like temporal variability or the frequency, and the context under which mate switching occurs. Taking advantage of a long-term genetic and space-use data set from tree sloths in our study site in Costa Rica, we aimed to more completely characterize the mating systems of these 2 species of tree sloths and test the hypothesis that in the absence of mate guarding and sperm competition, mating systems in both species of sloths would be shaped by strategies of females. Further, we predicted that observations of multiple paternity would increase when breeding was assessed over multiple seasons. We also predicted that females would tend to mate with relatively more productive males (i.e., males that sired more offspring). Finally, we used fine-scale movement and space-use information from radiomarked individuals to explore the potential role of female choice in the mating system of these 2 species. Our approach, combining genetic and space-use data for a large number of individuals across 4 years of study, provides new insights into the strategies behind mate selection that shape the mating system for 2 cryptic, solitary, and understudied species of mammals. Methods and Materials Study area We conducted fieldwork from February 2010 to May 2014 in an agro-ecosystem in the Caribbean coastal plain of northeastern Costa Rica (10.32°N, −83.59°W). The study area (4 km2) occurs within an agricultural landscape containing 3 general habitat types used by sloths: a cacao plantation planted underneath a diverse over story of shade trees; tropical forest that occurs in narrow (~20 m) riparian buffers and small patches of forest; and cattle pastures containing living fence rows and isolated legacy trees (Mendoza et al. 2015). The climate is wet and warm, with the rainy season typically starting in mid- to late April and continuing until January (Janzen 1983). Captures and radiotracking From February 2010 to May 2014, we captured 111 B. variegatus (78 adults-subadults and 33 juveniles) and 275 C. hoffmanni (214 adults-subadults and 61 juveniles) by hand from trees. We consider this to represent all, or nearly all, of the resident sloths within our study area. When captured sloths were sufficiently developed, we determined the sex by examining external genitalia and classified individuals into 1 of the following 3 stage classes: juvenile, subadult, or adult based on previously established body mass criteria (Pauli and Peery 2012; Peery and Pauli 2012). We marked all captured individuals with uniquely coded PIT tags (Biomark, Boise, Idaho) inserted subcutaneously between the shoulder blades. Males of adequate size were fitted with radiocollars (Mod-210; Telonics Inc., Mesa, Arizona); females were initially marked with uniquely identifiable color collars, which were then replaced with radiocollars in the 2nd year of the study. We generally obtained locations for sloths 5 to 6 times per month. Capturing, handling, and tracking were conducted as is stipulated and authorized by IACUC protocol A01424, and we adhered to the guidelines for the use of mammals in research set forth by the American Society of Mammalogists (Sikes et al. 2016). Paternity assignments We genotyped individual B. variegatus and C. hoffmanni using 13 and 15 previously developed microsatellite markers, respectively (Moss et al. 2011, 2012). For C. hoffmanni, however, we excluded 4 loci (D110, B102, D101, and B119) because they deviated from Hardy–Weinberg or linkage equilibrium (Peery and Pauli 2012). We extracted sloth DNA, conducted PCR reactions, and genotyped individuals following Pauli and Peery (2012) and Peery and Pauli (2012). We calculated observed and expected heterozygosity using Cervus v3.0.7 (Marshall et al. 1998; Kalinowski et al. 2007). We used standard likelihood approaches implemented in the program Cervus v3.0.7 (Marshall et al. 1998; Kalinowski et al. 2007) to assign paternity for the juveniles that were sampled with what we assumed were their biological mothers (juvenile was held by or located immediately adjacent to female); maternity was confirmed by checking that mother–offspring dyads shared at least 1 allele at all loci. For both species, we included all genotyped subadult and adult males as potential fathers to account for the possibility that some subadults in both species could have been reproductively active. We assumed a genotyping error rate of 0.01 and set the proportion of sampled candidate fathers at 85% based on the fact that almost all males encountered in our study area had previously been captured and sampled. We used logarithm of odds ratio (LOD) scores, which represent the difference in the likelihood of the 2 most likely candidate fathers, to assign paternity and to assess confidence in the assignment. We used both a relaxed confidence level of 80% and a strict confidence level of 95% to assess paternity, and in cases where confidence was only 80%, we only assigned paternity if there was spatial congruence between the mother and putative father. Characterizing space use To explore overlap in space use between males and females and identify possible mating events, we delineated space use with 95% minimum convex polygons (Calenge 2006) during the estimated estrus period for every female known to have produced an offspring, as well as all males in the vicinity of these females. We estimated the duration of estrus for B. variegatus as 5–8 months (Taube et al. 2001; Mühlbauer et al. 2006). We calculated a total of 20 minimum convex polygons for 11 individual B. variegatus (4 females [range = 5–26 locations] and 7 males [range = 5–56 locations]). All but 3 polygons were calculated with 20 or more locations; we estimated a polygon for 3 individuals with only 5 locations to explore potential contact between the males and females. We were unable to calculate minimum convex polygons for C. hoffmanni due to insufficient sample sizes during the estrus period. We also calculated core areas using 50% fixed kernel density estimates for 10 female B. variegatus (range = 29–275 locations) and 10 female C. hoffmanni (range = 57–210 locations) over the 4 years of study and tabulated the number of male territories that overlapped the core areas of each female (Calenge 2006). Statistical analyses We estimated reproductive skew in the 2 species using a subset of individuals observed in at least 3 of the 4 years of our study (i.e., “residents”). Limiting analyses of skew to residents minimized the likelihood that sloths not present or observed in most years would give the appearance of high levels of variation in reproduction among individuals. We tested if the reproductive output for males and females was skewed using a chi-square test (Krebs 1989). Moreover, we compared reproductive skew between species and between males and females with Fisher’s exact tests (Press et al. 1992). We evaluated whether females switched to males with higher reproductive success by comparing to a random expectation with a chi-square test. We tested if reproductive output of males was related to body size (a proxy for male quality) and the number of ha of forest habitat in the 50% core area (a proxy for habitat quality), or simply the number of females in a male’s 50% core area, using multiple linear regression for each species separately. We also tested whether the core area size, the number of males overlapping a female’s core area, and the reproductive output (number offspring sired) of the female’s mate differed between females that mated with a single male during the length of our study versus those females that mated with multiple males over time using t-tests. Results Paternity assignments We sampled and genotyped 85 individual B. variegatus (Supplementary Data SD1) for genetic-based parentage analysis (17 females, 35 males, and 33 juveniles). We assigned paternity to 29 juveniles with 95% confidence and the remaining 4 juveniles with 80% confidence. For C. hoffmanni, we tested and genotyped 182 individuals (44 females, 77 males, and 61 juveniles; Supplementary Data SD1), assigning paternity to 31 juveniles with 95% confidence, 16 juveniles with 80% confidence, and 14 with less than 80% confidence. For both species, all mothers and genetically assigned fathers shared at least 1 allele at all loci with their putative offspring. Our parentage assignments were further corroborated by the fact that all genetically assigned mothers were sampled holding their offspring and genetically assigned fathers occurred in close proximity to the assumed mother and had spatial contact in some moment in the breeding season. Reproductive skew We considered 13 male and 25 female B. variegatus and 39 male and 50 female C. hoffmanni as residents. Among residents, reproductive output of males was skewed in both species (B. variegatus: χ214 = 29.69, P < 0.01; C. hoffmanni: χ26 = 29.38, P < 0.01), with a high percentage of individuals siring 2 or fewer offspring (54% and 41%; Fig. 1). The level of reproductive skew among males was not statistically different between species (Fisher’s exact test7 = 6.09, P = 0.53). However, a single male B. variegatus sired 14 offspring, which represented 42% of juveniles for which paternity was assigned (Fig. 1a). We also note that the percentage of resident males that did not produce offspring was somewhat higher in C. hoffmanni than B. variegatus (38% versus 23%). Reproductive output was skewed in female C. hoffmanni (χ22 = 8.67, P = 0.01), but was not in female B. variegatus (χ23 = 1.4, P = 0.70). For C. hoffmanni, reproductive skew did not differ between males and females (Fisher’s exact test6 = 7.94, P = 0.22; Fig. 1b). Fig. 1. Open in new tabDownload slide Variation in reproductive output of resident (a) male and (b) female brown-throated three-toed sloths (Bradypus variegatus) and Hoffmann’s two-toed sloths (Choloepus hoffmanni) at our study site in northeastern Costa Rica, 2010–2013. Fig. 1. Open in new tabDownload slide Variation in reproductive output of resident (a) male and (b) female brown-throated three-toed sloths (Bradypus variegatus) and Hoffmann’s two-toed sloths (Choloepus hoffmanni) at our study site in northeastern Costa Rica, 2010–2013. Characterizing space use Mean core area size in B. variegatus was 9.5 ha for males (SD = 21.15) and 2.8 ha for females (SD = 3.95). Core areas of male B. variegatus overlapped with an average of 3.1 core areas of females (SD = 3.12). Core areas of female B. variegatus overlapped with an average of 1.7 core areas of males (SD = 1.01). C. hoffmanni possessed average core areas of 5.8 ha for males (SD = 7.64) and 1.7 ha for females (SD = 3.26). Core areas of male C. hoffmanni overlapped with an average of 1.8 core areas of females (SD = 1.16); core areas of females overlapped with an average of 1.5 core areas of males (SD = 0.97). Mate fidelity Females of both species exhibited a range of mating strategies. Of 10 female B. variegatus producing at least 2 offspring, 7 (70%) mated with multiple males, whereas only 3 (30%) exhibited mate fidelity (Fig. 2a). One female B. variegatus that produced offspring in 3 different years mated again with her 1st offspring’s father in the 3rd year after switching to a different male in the 2nd year (Fig. 2a). Of 14 female C. hoffmanni producing multiple offspring, 7 (50%) produced offspring with multiple males and the other 7 produced all of their offspring with a single mate (Fig. 2b). Fig. 2. Open in new tabDownload slide Patterns of mate switching among female (a) brown-throated three-toed sloths (Bradypus variegatus) and (b) Hoffmann’s two-toed sloths (Choloepus hoffmanni) at our study site in northeastern Costa Rica, 2010–2013. Letters denote sex (M = male; F = female) and numbers represent individual identities. Black cells = no data; white cells = no reproduction. Fig. 2. Open in new tabDownload slide Patterns of mate switching among female (a) brown-throated three-toed sloths (Bradypus variegatus) and (b) Hoffmann’s two-toed sloths (Choloepus hoffmanni) at our study site in northeastern Costa Rica, 2010–2013. Letters denote sex (M = male; F = female) and numbers represent individual identities. Black cells = no data; white cells = no reproduction. Female B. variegatus exhibited both mate fidelity and multiple paternity under different circumstances. Among females that mated with the same male in successive years, some remained within their mate’s home range in both years that they bred (Fig. 3a), whereas others mated with the same male in 2 different years despite the fact that their home range overlapped with those of multiple males in both breeding seasons (Fig. 3b). Among females that switched mates, some did so by shifting their home range to an area occupied by a different male in her 2nd breeding attempt (Fig. 4a), whereas others maintained similar home ranges across breeding seasons but simply mated with different co-occurring males (Fig. 4b). Fig. 3. Open in new tabDownload slide Two examples of mate fidelity in females of brown-throated three-toed sloths (Bradypus variegatus): (a) a female that overlapped with only a single male, and (b) a female that overlapped with multiple males at our study site in northeastern Costa Rica, 2010–2013. Polygons are 95% minimum convex polygons. Asterisks denote reproductively active males. Fig. 3. Open in new tabDownload slide Two examples of mate fidelity in females of brown-throated three-toed sloths (Bradypus variegatus): (a) a female that overlapped with only a single male, and (b) a female that overlapped with multiple males at our study site in northeastern Costa Rica, 2010–2013. Polygons are 95% minimum convex polygons. Asterisks denote reproductively active males. Fig. 4. Open in new tabDownload slide Two examples of mating with different males in different years by females of brown-throated three-toed sloths (Bradypus variegatus) at our study site in northeastern Costa Rica, 2010–2013: (a) a female that shifted its home range for her 2nd breeding attempt, and (b) a female that maintained a consistent home range across breeding seasons but mated with different males in the 2 seasons. Polygons are 95% minimum convex polygons. Fig. 4. Open in new tabDownload slide Two examples of mating with different males in different years by females of brown-throated three-toed sloths (Bradypus variegatus) at our study site in northeastern Costa Rica, 2010–2013: (a) a female that shifted its home range for her 2nd breeding attempt, and (b) a female that maintained a consistent home range across breeding seasons but mated with different males in the 2 seasons. Polygons are 95% minimum convex polygons. We did not find a significant relationship between the number of offspring sired by males and male body size, amount of forested habitat in the core area, or the number of females that overlapped the male’s core area for either species (all P > 0.15; Supplementary Data SD2). Females that mated with a single male tended to so with more successful males than females that mated with multiple males for C. hoffmanni (t13 = 2.95, P = 0.01), but this difference was only marginally significant for B. variegatus (t9 = 1.91, P = 0.09; Fig. 5). Moreover, mate switching was distributed non-randomly among C. hoffmanni (χ22 = 8.67, P = 0.01), with females tending to mate with more reproductively active males; we did not detect any pattern in mate switching among female B. variegatus (χ22 = 2.36, P = 0.31). We did not detect differences in the number of overlapping males (B. variegatus: t7 = 0.53, P = 0.61; C. hoffmanni: t7 = 0.48, P = 0.61) or in the sizes of the core areas (B. variegatus: t7 = −0.9, P = 0.39; C. hoffmanni: t7 = 0.48, P = 0.65) between females that mated with a single male and females that had multiple male mates for either species. Fig. 5. Open in new tabDownload slide Mean number of offspring (± 1 SD) sired by males mated with females that bred with a single versus multiple males in brown-throated three-toed sloth (Bradypus variegatus) and Hoffmann’s two-toed sloth (Choloepus hoffmanni) at our study site in northeastern Costa Rica, 2010–2013. Fig. 5. Open in new tabDownload slide Mean number of offspring (± 1 SD) sired by males mated with females that bred with a single versus multiple males in brown-throated three-toed sloth (Bradypus variegatus) and Hoffmann’s two-toed sloth (Choloepus hoffmanni) at our study site in northeastern Costa Rica, 2010–2013. Discussion Female sloths often mated with multiple males over their lifetime; indeed, 70% of female B. variegatus and 50% of female C. hoffmanni switched mates among years at least once during the study. Our analysis of individual movements suggested that reproductive strategies of females played an important role in determining pair matings. Our study, which spanned 4 breeding cycles in both species, suggests that mating with more than 1 male over time is common in sloths, and greater than previously believed. The only previous study of the mating systems of C. hoffmanni was limited to a single breeding cycle and was, therefore, unable to assess the prevalence of sequential matings with multiple males in the species (Peery and Pauli 2012). On the other hand, Pauli and Peery (2012), working over 2 breeding seasons, found that only 25% of female B. variegatus mated with multiple males. Herein, the percentage of female B. variegatus observed mating with more than 1 male increased over time from 10% in 2011 to 30% by 2012 to 70% by 2013. Given that our study spanned multiple breeding cycles and the female sloths in our study were adult residents (with a maximum life span of 12 years—Gilmore et al. 2001), we consider it unlikely that the observed sequential mating with multiple males was primarily a consequence of our inadequate sampling of adult sloths, or a result of the age structure of female sloths (e.g., lack of reproductive experience among young females), but rather was a female strategy. Our findings highlight the importance of long-term space-use and genetic studies for understanding the mating systems of uniparous species. In general, mating with multiple males can be a female strategy to confuse paternity and avoid infanticide (Hrdy 1979; Wolff and Macdonald 2004), to maximize genetic diversity among their offspring (Brooked et al. 1990; Murie 1996; Yasui 2001), to switch to a higher-quality mate (Jennions and Petrie 2000), or as consequence of sperm competition. Among tree sloths, forced copulations and infanticide have not been reported, and are unlikely based on the absence of sexual size dimorphism and their low activity levels (Pauli and Peery 2012; Peery and Pauli 2012). Similarly, the proportional size of testes in tree sloth species is small (less than half that expected based on body size—Britton 1941), suggesting that sperm competition is not an important component of the mating system (Kenagy and Trombulak 1986). Rather, we suggest that female sloths employ mate switching as a strategy to enhance genetic diversity or possibly to select higher-quality males (Wolff and Macdonald 2004; Clutton-Brock and McAuliffe 2009). The presence of multiple male sloths within female home ranges during estrus provides the opportunity for females to select a male from a larger pool of suitors, as has been observed in other mammals with similar mating strategies (Fisher and Lara 1999; Garnier et al. 2001). While the mating systems of both sloth species exhibited elements of polygyny, they were characterized by intermediate skew in reproductive success of males. The observed distribution of male reproductive success could have been influenced by mortality, but this factor likely had little effect given that males present in fewer than 3 of 4 years were excluded from analyses. Reproductive output of males is generally predicted to be less skewed in solitary than social mammals because males are less able to monopolize multiple females (Emlen and Oring 1977; Clutton-Brock 1989; Fisher and Lara 1999). However, even for solitary species, reproductive skew can emerge as a consequence of individual variation in physical characteristics and territory quality of the male (Emlen and Oring 1977; Clutton-Brock 1989; Sandell 1989). We did not detect a relationship between reproductive output of males and body mass, amount of forested habitat in the core area, or the number of females in a male’s core area. Rather, variable breeding success in male sloths could be driven by female choice for unknown male physical characteristics (other than just body size) or finer-scale habitat characteristics than measured in this study. Male B. variegatus possess a dorsal orange speculum with a black vertical stripe that varies in size and coloration and has been suggested to be a form of either visual or olfactory sexual ornamentation; no such apparent ornamentation exists for C. hoffmanni. It is therefore possible that female B. variegatus are selecting males based on this, or potentially on other visual, olfactory, or auditory cues. Alternatively, female tree sloths could be selecting males based on the specific tree composition in their territories, particularly Cecropia spp. and Coussapoa spp. trees by B. variegatus (Mendoza et al. 2015). More study is needed to distinguish the importance of male characteristics versus habitat quality in female choice of mates. Species-specific differences in habitat use and spatial dispersion may have contributed to greater reproductive skew in male B. variegatus than in male C. hoffmanni. Although we did not detect a relationship between reproductive output of males and the number of females in the male’s core area for either species, B. variegatus tends to cluster in the small patches and thin strips of intact riparian forest (Pauli and Peery 2012; Mendoza et al. 2015). C. hoffmanni, on the other hand, utilizes a broader range of habitat and is more uniformly distributed across the study area (Peery and Pauli 2012; Mendoza et al. 2015). Thus, the clustering of B. variegatus within small forest fragments could enhance opportunities for females to select high-quality males and ultimately contribute to increased reproductive skew among males. Such a pattern has been observed among other arboreal mammals that exhibit similar limited mobility, where a very few males gain mating access to multiple females with little effort (Sweitzer and Berger 1998). Female B. variegatus exhibited a high level of mate switching, which occurred along with 2 different patterns of space use. On one hand, some females were observed shifting their activity center away from a previous center to overlap with a new mate. Other females selected a new mate without moving their activity center despite the opportunity to mate with their previous male. Females of several species increase movements or expand their home range during estrus to enhance the probability that other males find them (Johnson 1989; Fisher and Lara 1999), but this behavior is not clear evidence of female choice because male success may be a consequence of intra-sexual competition (Clutton-Brock and McAuliffe 2009). However, the presence of 2 strategies for mate switching by females, as well as females that continue to mate with a single male, reinforces the idea that female choice is present and drives the mating system in these species. Indeed, previous authors have suggested that females play an active role in the mating strategy of tree sloths, and even attempt to attract potential male suitors (Richard-Hansen and Taube 1997; Bezerra et al. 2008); our findings provide support for this concept. Collectively, our findings highlight the complexity and dynamic nature of vertebrate mating systems, as well as the role that female strategies can play in structuring mating systems. Our work also reveals the importance of long-term genetic and space-use studies, especially for uniparous species, in rigorously capturing individual mating strategies and characterizing the emergent mating system. Supplementary Data Supplementary data are available at Journal of Mammalogy online. Supplementary Data SD1. Genotypic information for brown-throated three-toed sloths (Bradypus variegatus) and Hoffmann’s two-toed sloth (Choloepus hoffmanni) in northeastern Costa Rica, 2010 to 2013. Ho &#x003D; observed heterozygosity, He &#x003D; expected heterozygosity, PIC &#x003D; polymorphic information content, NE-2P &#x003D; non-exclusion probabilities for one candidate parent given the genotype of known parent of the opposite sex. 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TI - Individual reproductive strategies shape the mating system of tree sloths
JO - Journal of Mammalogy
DO - 10.1093/jmammal/gyx094
DA - 2017-10-03
UR - https://www.deepdyve.com/lp/oxford-university-press/individual-reproductive-strategies-shape-the-mating-system-of-tree-nqPRJYR4RM
SP - 1417
VL - 98
IS - 5
DP - DeepDyve
ER -