Evol Ecol Res 20: 265-278 (2019)     Full PDF if your library subscribes.

Resources are more important than predation in driving the size at maturation of freshwater Threespine stickleback (Gasterosteus aculeatus)

Abdul R. Singkam^1,2 and Andrew D.C. MacColl¹

¹School of Life Sciences, The University of Nottingham, Nottingham, UK and ²Pendidikan Biologi, JPMIPA-FKIP, Universitas Bengkulu, Indonesia

Correspondence: A.R. Singkam, Pendidikan Biologi, JPMIPA-FKIP, Universitas Bengkulu, Indonesia 38371. email: arsingkam@unib.ac.id

ABSTRACT

Background: Resource availability and predation are thought to be the most important ecological factors shaping age at maturation. They are expected to have a similar effect in causing populations to mature earlier, but a contrasting effect on size at maturation. Greater resource supplies have a positive effect on size at maturation by increasing growth rate, whereas heavier predation has a negative effect since it induces populations to mature earlier (and thus at smaller size).

Question: Is resource availability or predation pressure more important in shaping the size at maturation when resources and predation covary in the environment?

Organism: Freshwater Threespine stickleback (Gasterosteus aculeatus).

Field site: Natural lochs on the Scottish island of North Uist.

Methods: We estimated size at maturation using two different approaches: probabilistic maturation reaction norm (PMRN) and Stearns’ size at maturation.

Results: Size at maturation was strongly influenced by resource supply but not by predation. We obtained this result with both approaches: PMRN and Stearns’ size at maturation. Populations in higher resource environments, even with higher predation, tend to mature as larger and older individuals. The large increase in fecundity achieved by delaying maturation could provide an explanation for this. Populations living in resource-rich environments also clearly have a faster growth rate, as indicated by a larger average size of individuals at age one year. On the other hand, populations with higher predation have a significantly lower life span, as indicated by a lower proportion of fish older than one year.

Keywords: maturation event, PMRN, predation, resources, Threespine stickleback.

DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.

 

        © 2019 Abdul R. Singkam. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.