Patterns of evolution over different time-scales: An adaptive dynamics approach

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

In this thesis we use the framework of adaptive dynamics and bifurcation analysis to study evolution with a spatially explicit population model in an abiotic environment that changes over geological timescales. Essentially, this process models the fossil record. In accordance with previous studies, we find that branching on an environmental gradient occurs when the environmental gradient is not too steep or shallow. Even though branching on a steep gradient is not possible for a monomorphic population, we find an interesting evolutionary hysteresis effect: depending on environmental history it is possible for a polymorphic population to evolve and inhabit a steep environmental gradient on which monomorphic branching does not occur. Further, we find that it is typically intermediate phenotypes that undergo branching. Here evolution occurs through small mutational steps and via an invasion-substitution sequence. However, over the timescales of the fossil record this gradual evolution may appear as punctuated. In a slowly changing environment intermediate phenotypes are also more prone to extinction, whereas in a fast changing environment extreme phenotypes are seen to be in greater danger. We use this modeling approach to study a partially unexplained pattern of diversification of hoofed mammals in Eurasia during the Late Miocene (11-5 Ma). We also use game theoretical methods to study the evolution of trade-offs: another pattern ubiquitous in nature. Specifically, we model an annual plant population and study the correlation of seed size and germination time. We do not assume any physiological constraints on the production of seeds of any combination of size and germination time. However, we find that typically an Evolutionarily Stable Strategy is such that a correlation emerges between the two. This raises the general question whether trade-offs observed in nature are caused by physiological constraints or whether they are just implementations of an evolutionarily beneficial strategy.
Original languageEnglish
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Gyllenberg, Mats, Supervisor
  • Fortelius, Mikael, Supervisor
  • Geritz, Stefanus, Supervisor
Award date11 Apr 2017
Place of PublicationHelsinki
Publisher
Print ISBNs978-951-51-3076-1
Electronic ISBNs978-951-51-3077-8
Publication statusPublished - 11 Apr 2017
MoE publication typeG5 Doctoral dissertation (article)

Fields of Science

  • 111 Mathematics
  • 1181 Ecology, evolutionary biology

Cite this

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title = "Patterns of evolution over different time-scales: An adaptive dynamics approach",
abstract = "In this thesis we use the framework of adaptive dynamics and bifurcation analysis to study evolution with a spatially explicit population model in an abiotic environment that changes over geological timescales. Essentially, this process models the fossil record. In accordance with previous studies, we find that branching on an environmental gradient occurs when the environmental gradient is not too steep or shallow. Even though branching on a steep gradient is not possible for a monomorphic population, we find an interesting evolutionary hysteresis effect: depending on environmental history it is possible for a polymorphic population to evolve and inhabit a steep environmental gradient on which monomorphic branching does not occur. Further, we find that it is typically intermediate phenotypes that undergo branching. Here evolution occurs through small mutational steps and via an invasion-substitution sequence. However, over the timescales of the fossil record this gradual evolution may appear as punctuated. In a slowly changing environment intermediate phenotypes are also more prone to extinction, whereas in a fast changing environment extreme phenotypes are seen to be in greater danger. We use this modeling approach to study a partially unexplained pattern of diversification of hoofed mammals in Eurasia during the Late Miocene (11-5 Ma). We also use game theoretical methods to study the evolution of trade-offs: another pattern ubiquitous in nature. Specifically, we model an annual plant population and study the correlation of seed size and germination time. We do not assume any physiological constraints on the production of seeds of any combination of size and germination time. However, we find that typically an Evolutionarily Stable Strategy is such that a correlation emerges between the two. This raises the general question whether trade-offs observed in nature are caused by physiological constraints or whether they are just implementations of an evolutionarily beneficial strategy.",
keywords = "111 Mathematics, 1181 Ecology, evolutionary biology",
author = "Toivonen, {Jaakko Tapio}",
year = "2017",
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publisher = "University of Helsinki",
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Patterns of evolution over different time-scales : An adaptive dynamics approach. / Toivonen, Jaakko Tapio.

Helsinki : University of Helsinki, 2017. 99 p.

Research output: ThesisDoctoral ThesisCollection of Articles

TY - THES

T1 - Patterns of evolution over different time-scales

T2 - An adaptive dynamics approach

AU - Toivonen, Jaakko Tapio

PY - 2017/4/11

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N2 - In this thesis we use the framework of adaptive dynamics and bifurcation analysis to study evolution with a spatially explicit population model in an abiotic environment that changes over geological timescales. Essentially, this process models the fossil record. In accordance with previous studies, we find that branching on an environmental gradient occurs when the environmental gradient is not too steep or shallow. Even though branching on a steep gradient is not possible for a monomorphic population, we find an interesting evolutionary hysteresis effect: depending on environmental history it is possible for a polymorphic population to evolve and inhabit a steep environmental gradient on which monomorphic branching does not occur. Further, we find that it is typically intermediate phenotypes that undergo branching. Here evolution occurs through small mutational steps and via an invasion-substitution sequence. However, over the timescales of the fossil record this gradual evolution may appear as punctuated. In a slowly changing environment intermediate phenotypes are also more prone to extinction, whereas in a fast changing environment extreme phenotypes are seen to be in greater danger. We use this modeling approach to study a partially unexplained pattern of diversification of hoofed mammals in Eurasia during the Late Miocene (11-5 Ma). We also use game theoretical methods to study the evolution of trade-offs: another pattern ubiquitous in nature. Specifically, we model an annual plant population and study the correlation of seed size and germination time. We do not assume any physiological constraints on the production of seeds of any combination of size and germination time. However, we find that typically an Evolutionarily Stable Strategy is such that a correlation emerges between the two. This raises the general question whether trade-offs observed in nature are caused by physiological constraints or whether they are just implementations of an evolutionarily beneficial strategy.

AB - In this thesis we use the framework of adaptive dynamics and bifurcation analysis to study evolution with a spatially explicit population model in an abiotic environment that changes over geological timescales. Essentially, this process models the fossil record. In accordance with previous studies, we find that branching on an environmental gradient occurs when the environmental gradient is not too steep or shallow. Even though branching on a steep gradient is not possible for a monomorphic population, we find an interesting evolutionary hysteresis effect: depending on environmental history it is possible for a polymorphic population to evolve and inhabit a steep environmental gradient on which monomorphic branching does not occur. Further, we find that it is typically intermediate phenotypes that undergo branching. Here evolution occurs through small mutational steps and via an invasion-substitution sequence. However, over the timescales of the fossil record this gradual evolution may appear as punctuated. In a slowly changing environment intermediate phenotypes are also more prone to extinction, whereas in a fast changing environment extreme phenotypes are seen to be in greater danger. We use this modeling approach to study a partially unexplained pattern of diversification of hoofed mammals in Eurasia during the Late Miocene (11-5 Ma). We also use game theoretical methods to study the evolution of trade-offs: another pattern ubiquitous in nature. Specifically, we model an annual plant population and study the correlation of seed size and germination time. We do not assume any physiological constraints on the production of seeds of any combination of size and germination time. However, we find that typically an Evolutionarily Stable Strategy is such that a correlation emerges between the two. This raises the general question whether trade-offs observed in nature are caused by physiological constraints or whether they are just implementations of an evolutionarily beneficial strategy.

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