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COULD SENESCENCE BE ADAPTIVE? CAUSES AND CONSEQUENCES OF AGING ACROSS THE TREE OF LIFE

Periodic Reporting for period 1 - WHYAGE (COULD SENESCENCE BE ADAPTIVE? CAUSES AND CONSEQUENCES OF AGING ACROSS THE TREE OF LIFE)

Reporting period: 2017-05-01 to 2019-04-30

With increasing age, we are more likely to die, and less likely to reproduce. This is ‘senescence’. Unlike humans, not everything senesces: we now know that some organisms have unchanging or even increasing survival and reproduction with age ('negligible' or 'negative' senescence respectively). Survival and reproduction control whether populations increase or decline, so understanding aging is important for conserving threatened, declining species. Yet, we don't even know how such diverse aging has evolved. The WHYAGE project links diverse aging patterns to population dynamics of plants and animals across the whole tree of life, to understand the consequences of aging for populations, and gain insight into how diverse aging patterns potentially evolved.
"WHYAGE hypothesised that species with different types of aging would show different population dynamics. We show this to be true in animals, but not plants. Animal species with extreme senescence or extreme negative senescence can bounce back quickly from environmental disturbances (such as fire, hurricanes or disease epidemics), so avoiding population decline. Animal species with negligible senescence cannot do this. This result helps foresee how a species may respond to a disturbance, which is helpful for conservation, and lends credibility to our hypothesis that diverse aging has evolved to mitigate repeated exposures to certain environmental disturbances.

Our ability to determine these results was only possible by developing our own mathematical measures of aging, and of the resilience of species to environmental disturbances. These methods have already been recognised by other academics, leading to further collaborations using the methods to explore the evolution of aging across plant and animal species. The methods are published (see below); other results are being prepared for publication.

The work has also been disseminated through organised conference sessions, and invited talks at institutes worldwide. Completion of the work was facilitated through training courses attended by the fellow, a secondment, and research visits (see below).



ACADEMIC PUBLICATIONS---

Stott & Baudisch (2019) ""A pace and shape perspective on fertility"". Methods in Ecology and Evolution. DOI 10.1111/2041-210X.13289


ACTIVITIES---


ORGANISED CONFERENCE SESSIONS:

""Resilience without borders: how do different ecological disciplines measure and define resilience?""
12 Dec 2019, British Ecological Society (BES) Annual Meeting

""All creatures fast and slow""
19 Dec 2018, BES Annual Meeting


INVITED PRESENTATIONS:

""Transient dynamics... a consequence of aging?""
11-15 Aug 2019, Ecological Society of America (ESA) Annual Meeting

""Non-stable dynamics in evolutionary demography across the tree of life""
29th Mar 2019, University of Oxford Zoology Seminar Series

""No more equilibria, please! Non-stable dynamics in evolutionary demography""
23 May 2018, University of Zürich IEU seminar series

""Linking evolutionary causes and ecological consequences of aging [etc.], across the tree of life""
15 Nov 2017, University of Sheffield Animal and Plant Sciences ""Triple-E"" seminar series

""Aging and population dynamics across the tree of life""
19 May 2017, MaxNetAging annual conference, MPIDR Rostock


CONFERENCE PRESENTATIONS:

""A pace and shape perspective on fertility""
11 Jan 2019, Nordic Society OIKOS Danish chapter annual meeting


RESEARCH VISITS:

University of Exeter, Centre for Ecology & Conservation
12 → 14 Dec 2018 & 4 → 6 Apr 2018


SECONDMENT:

University of Zürich, Dept. of Evolutionary Eiology & Environmental Studies
15 May → 6 Apr 2018


WORKSHOPS ATTENDED:

""Using geiger, phytools, and other computational tools to study macroevolution on phylogenies""
16 Jul 2019 → 24 July 2019, Heraklion, Greece

""All Creatures Fast and Slow: comparative life history using matrix population models""
17 → 20 Dec 2017

""COMPADRE/COMADRE R Development""
2 → 6 Dec 2017


WORKSHOPS (CO)-ORGANISED:

""Matrix models for population ecology""
28 May 2019 → 29 May 2019, University of Southern Denmark

""Population modelling... without that wretched coding""
18 Dec 2018, BES Annual Meeting 2018

""Introduction to Matrix Population Models and Comparative Population Biology Using the COM(P)ADRE Matrix Databases""
16 Dec 2018, BES Annual Meeting 2018

""NERC Advanced Training Short Course: Stage-based models in ecology, evolution and conservation biology""
22 → 26 Jan 2018, University of Sheffield

""Introduction to Matrix Population Models and Comparative Population Biology Using the COM(P)ADRE Matrix Databases""
6 Aug 2017, ESA Annual Meeting 2017"
"State of the art:
Aging is diverse across the tree of life, with organisms showing senescence, negative senescence and negligible senescence. These traits should only evolve if they enable ""survival of the fittest""; a growing population is 'fit'. At the project start, there existed aging measures for survival, but not reproduction. Analyses of survival aging had been done for plants, but not animals. No study had linked these patterns to population dynamics.

Progress beyond the state of the art:
WHYAGE has addressed these gaps in knowledge, developing new measures for aging in both reproduction and survival. The project applied these measures to both plants and animals, and linked this to population dynamics to determine how aging affects fitness. We may assume that senescence is bad for fitness, but our analyses show this isn't necessarily the case. Further collaborative work is now generating frameworks for understanding population dynamics and life history evolution in light of aging. In collaboration with the University of Oxford, we have developed a framework for understanding the 'resilience' of populations to disturbances. In a multinational collaboration, we have developed a framework to understand life history beyond aging, including other life history traits.



EXPECTED RESULTS

ARTICLES:

""Are transient population dynamics a symptom of aging?""
Main results of project: aging affects transient dynamics.

""R packages for projection matrices""
Journal articles that present the R software packages developed during the project.

""A resilience framework for population ecology""
A framework for understanding the 'resilience' of populations to disturbances

""All creatures great and small""
A framework for how life histories are (and should be) measured including multiple life history and functional traits.


SOFTWARE:

Rcompadre and Rage
Two R packages to for managing the com(p)adre data that's used for the WHYAGE project, and calculating life history measures (including those developed during the WHYAGE project).

ShinyPop
This is an R Shiny WebApp that lets the user explore the com(p)adre databases and calculate population dynamics and life history measures, as well as graph results.



POTENTIAL IMPACTS

Understanding aging is of great use to applied ecology and conservation. For species with unknown age, it may be possible using the methods we have developed to calculate expected survival / reproduction age trajectories and therefore possible population dynamics. If a species' survival and reproduction aren't known, inferring aging type may be possible from related species, or species with similar ecology. This will help managers and conservationists decide upon appropriate management techniques to manage and conserve by either curbing or boosting population growth."
Different types of reproductive aging. L-R: increasing, symmetrical, decreasing with age.