Extrinsic mortality and senescence: a guide for the perplexed
Do environments or species traits that lower the mortality of individuals create selection for delaying senescence? Reading the literature creates an impression that mathematically oriented biologists cannot agree on the validity of George Williams' prediction (who claimed 'yes'). The...
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2023-03-01
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| Online Access: | https://peercommunityjournal.org/articles/10.24072/pcjournal.253/ |
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| author | de Vries, Charlotte Galipaud, Matthias Kokko, Hanna |
| author_facet | de Vries, Charlotte Galipaud, Matthias Kokko, Hanna |
| author_sort | de Vries, Charlotte |
| collection | DOAJ |
| description | Do environments or species traits that lower the mortality of individuals create selection for delaying senescence? Reading the literature creates an impression that mathematically oriented biologists cannot agree on the validity of George Williams' prediction (who claimed 'yes'). The abundance of models and opinions may bewilder those that are new to the field. Here we provide heuristics as well as simple models that outline when the Williams prediction holds, why there is a ‘null model’ where extrinsic mortality does not change the evolution of senescence at all, and why it is also possible to expect the opposite of William’s prediction, where increased extrinsic mortality favours slower senescence. We hope to offer intuition by quantifying how much delaying the ‘placement’ of an offspring into the population reduces its expected contribution to the gene pool of the future. Our first example shows why sometimes increased extrinsic mortality has no effect (the null result), and why density dependence can change that. Thereafter, a model with ten different choices for population regulation shows that high extrinsic mortality favours fast life histories (Williams) if increasing density harms the production of juveniles or their chances to recruit into the population. If instead increasing density harms the survival of older individuals in a population, then high extrinsic mortality favours slow life histories (anti-Williams). We discuss the possibility that empirically found Williams-like patterns provide indirect evidence for population regulation operating via harming the production or fitness prospects of juveniles, as opposed to the survival of established breeders.
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| format | Article |
| id | doaj-art-c1274658b1724259926f6781e5f90e28 |
| institution | Kabale University |
| issn | 2804-3871 |
| language | English |
| publishDate | 2023-03-01 |
| publisher | Peer Community In |
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| series | Peer Community Journal |
| spelling | doaj-art-c1274658b1724259926f6781e5f90e282025-02-07T10:16:49ZengPeer Community InPeer Community Journal2804-38712023-03-01310.24072/pcjournal.25310.24072/pcjournal.253Extrinsic mortality and senescence: a guide for the perplexed de Vries, Charlotte0https://orcid.org/0000-0001-8955-0479Galipaud, Matthias1Kokko, Hanna2https://orcid.org/0000-0002-5772-4881Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands; Department of Biological and Environmental Science University of Jyväskylä, Jyväskylä, Finland; Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, SwitzerlandDepartment of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland; Swiss Data Science Center, Turnerstrasse 1, 8092, Zurich, SwitzerlandDepartment of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland; Konrad Lorenz Institute of Ethology University of Veterinary Medicine Vienna, Austria; Faculty of Biological and Environmental Sciences University of Helsinki, Helsinki, Finland; Institute for Organismic and Molecular Evolution, Johannes Gutenberg-University Mainz, Mainz, GermanyDo environments or species traits that lower the mortality of individuals create selection for delaying senescence? Reading the literature creates an impression that mathematically oriented biologists cannot agree on the validity of George Williams' prediction (who claimed 'yes'). The abundance of models and opinions may bewilder those that are new to the field. Here we provide heuristics as well as simple models that outline when the Williams prediction holds, why there is a ‘null model’ where extrinsic mortality does not change the evolution of senescence at all, and why it is also possible to expect the opposite of William’s prediction, where increased extrinsic mortality favours slower senescence. We hope to offer intuition by quantifying how much delaying the ‘placement’ of an offspring into the population reduces its expected contribution to the gene pool of the future. Our first example shows why sometimes increased extrinsic mortality has no effect (the null result), and why density dependence can change that. Thereafter, a model with ten different choices for population regulation shows that high extrinsic mortality favours fast life histories (Williams) if increasing density harms the production of juveniles or their chances to recruit into the population. If instead increasing density harms the survival of older individuals in a population, then high extrinsic mortality favours slow life histories (anti-Williams). We discuss the possibility that empirically found Williams-like patterns provide indirect evidence for population regulation operating via harming the production or fitness prospects of juveniles, as opposed to the survival of established breeders. https://peercommunityjournal.org/articles/10.24072/pcjournal.253/ |
| spellingShingle | de Vries, Charlotte Galipaud, Matthias Kokko, Hanna Extrinsic mortality and senescence: a guide for the perplexed Peer Community Journal |
| title | Extrinsic mortality and senescence: a guide for the perplexed
|
| title_full | Extrinsic mortality and senescence: a guide for the perplexed
|
| title_fullStr | Extrinsic mortality and senescence: a guide for the perplexed
|
| title_full_unstemmed | Extrinsic mortality and senescence: a guide for the perplexed
|
| title_short | Extrinsic mortality and senescence: a guide for the perplexed
|
| title_sort | extrinsic mortality and senescence a guide for the perplexed |
| url | https://peercommunityjournal.org/articles/10.24072/pcjournal.253/ |
| work_keys_str_mv | AT devriescharlotte extrinsicmortalityandsenescenceaguidefortheperplexed AT galipaudmatthias extrinsicmortalityandsenescenceaguidefortheperplexed AT kokkohanna extrinsicmortalityandsenescenceaguidefortheperplexed |