Scientific REPORTS | (2018) 8:4517 | DOI:10.1038/s41598-018-22789-6
Selection of trilateral continuums
of life history strategies under food
The study of life history strategies has a long history in ecology and evolution, but determining
the underlying mechanisms driving the evolution of life history variation and its consequences for
population regulation remains a major challenge. In this study, a food web model with constant
environmental conditions was used to demonstrate how multi-species consumer–resource interactions
(food-web interactions) can create variation in the duration of the adult stage, age of maturation, and
fecundity among species. The model included three key ecological processes: size-dependent species
interactions, energetics, and transition among developmental stages. Resultant patterns of life history
variation were consistent with previous empirical observations of the life history strategies of aquatic
organisms referred to as periodic, equilibrium, and opportunistic strategies (trilateral continuums of life
history strategies). Results from the simulation model suggest that these three life history strategies
can emerge from food web interactions even when abiotic environmental conditions are held constant.
e trilateral life history model has been proposed to describe variation in observed life history strategies among
. According to the model, life history variation can be predicted by trade-os among three variables: the
age of maturation (aecting generation time), investment per ospring (aecting survival to the adult stage), and
fecundity. e endpoints of these three variables are termed equilibrium, periodic, and opportunistic strategies.
is life history model is an empirically derived model and considered an extension of the traditional k- vs.
r-selection life history model. Because dierent natural resource management and biological conservation strate-
gies are required for organisms with dierent life histories
, understanding the cause of these life history patterns
is critically important.
ere is a long history of studies investigating the factors that aect life history strategies in general
Many of these studies have focused on the eects of environmental variation
, or the relative importance of
environmental variation and density dependent processes
. For example, Winemiller and Rose
the causes of the trilateral life history variations to dierences in physical environmental conditions experienced
by organisms. However, species interactions are another important process potentially aecting the selection of
life history strategies
. For example, life history strategies of guppies (Poecilia reticulata) were aected by the
predators they experience
. Nevertheless, the importance of species interactions in the studies of life history evo-
lution is still underappreciated. is is especially true with the studies of trilateral life history variations as most
recent studies focused on the eects of physical environmental conditions
. Consequently, it is still not clear
what types of life history strategies are selected when multiple stage-structured populations of dierent species
are experiencing consumer-resource interactions.
e objective of the current study was to demonstrate the role of consumer–resource interactions in shaping
the life history strategies of animal species, using a food web model consisting of multiple stage-structured pop-
ulations of dierent species. e model was used for investigating the six properties of life history strategies of
persisting species: duration of the adult stage, generation time, age of maturation, percent of ospring that survive
to maturity, average fecundity, and longevity at birth (Table1).
e food web model was derived from basic energetic concepts to accommodate the complexity of food
(Table2). e model incorporated size-dependent consumer–resource interactions; energy use for devel-
opment, survival, and reproduction (energetics); and transitions of individuals among developmental stages
(stage-structured populations). Size dependency in consumer-resource interactions is common in aquatic sys-
. Energy is one of the important currencies for estimating costs for organisms
, and life history strategies
Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX, 77843-2258, USA.
Correspondence and requests for materials should be addressed to M.F. (email: firstname.lastname@example.org)
Received: 29 June 2017
Accepted: 1 March 2018
Published: xx xx xxxx