Search results for "muuntelu"

Seasonal feeding strategies of subarctic zooplankton

2012

Maternally‐transferred thyroid hormones and life‐history variation in birds

2022

1. In vertebrates, thyroid hormones (THs) play an important role in the regulation of growth, development, metabolism, photoperiodic responses and migration. Maternally transferred THs are important for normal early-phase embryonic development when embryos are not able to produce endogenous THs. Previous studies have shown that variation in maternal THs within the physiological range can influence offspring phenotype. 2. Given the essential functions of maternal THs in development and metabolism, THs may be a mediator of life-history variation across species. 3. We tested the hypothesis that differences in life histories are associated with differences in maternal TH transfer across species…

Fitness and viability of small populations : the effects of genetic drift, inbreeding, and interpopulation hybridization

2012

Implications of heat waves on immune defence, life history traits, and adaptive potential : a snail's perspective

2014

Range expansion to novel environments : evolutionary physiology and genetics in Leptinotarsa decemlineata

2010

Safety in Numbers: How Color Morph Frequency Affects Predation Risk in an Aposematic Moth

2021

Polymorphic warning signals in aposematic systems are enigmatic because predator learning should favor the most common form, creating positive frequency-dependent survival. However, many populations exhibit variation in warning signals. There are various selective mechanisms that can counter positive frequency-dependent selection and lead to temporal or spatial warning signal diversification. Examining these mechanisms and their effects requires first confirming whether the most common morphs are favored at both local and regional scales. Empirical examples of this are uncommon and often include potentially confounding factors, such as a lack of knowledge of predator identity and behavior. …

Heterozygote advantage and pleiotropy contribute to intraspecific color trait variability

2022

The persistence of intrapopulation phenotypic variation typically requires some form of balancing selection because drift and directional selection eventually erode genetic variation. Heterozygote advantage remains a classic explanation for the maintenance of genetic variation in the face of selection. However, examples of heterozygote advantage, other than those associated with disease resistance, are rather uncommon. Across most of its distribution, males of the aposematic moth Arctia plantaginis have two hindwing phenotypes determined by a heritable one locus-two allele polymorphism (genotypes: WW/Wy = white morph, yy = yellow morph). Using genotyped moths, we show that the presence of o…

Evolution of signal diversity: predator-prey interactions and the maintenance of warning colour polymorphism in the wood tiger moth Arctia plantaginis

2017

Aposematic organisms avoid predation by advertising defences with warning signals. The theory of aposematism predicts warning signal uniformity, yet variation in warning coloration is widespread. The chemically defended wood tiger moth Arctia plantaginis shows both geographic variation and local polymorphism in warning coloration. In this thesis, I studied whether predation by local avian predators is driving the evolution of wood tiger moth warning colours. The close relatives of the wood tiger moth designated here to genus Arctia do not show similar colour polymorphism. The wood tiger moth is thus apparently under evolutionary radiation and provides a natural laboratory for observing curr…

The impact of life stage and pigment source on the evolution of novel warning signal traits

2021

Our understanding of how novel warning color traits evolve in natural populations is largely based on studies of reproductive stages and organisms with endogenously produced pigmentation. In these systems, genetic drift is often required for novel alleles to overcome strong purifying selection stemming from frequency-dependent predation and positive assortative mating. Here, we integrate data from field surveys, predation experiments, population genomics, and phenotypic correlations to explain the origin and maintenance of geographic variation in a diet-based larval pigmentation trait in the redheaded pine sawfly (Neodiprion lecontei), a pine-feeding hymenopteran. Although our experiments c…

Diversity in warning coloration: selective paradox or the norm?

2019

Aposematic theory has historically predicted that predators should select for warning signals to converge on a single form, as a result of frequency-dependent learning. However, widespread variation in warning signals is observed across closely related species, populations and, most problematically for evolutionary biologists, among individuals in the same population. Recent research has yielded an increased awareness of this diversity, challenging the paradigm of signal monomorphy in aposematic animals. Here we provide a comprehensive synthesis of these disparate lines of investigation, identifying within them three broad classes of explanation for variation in aposematic warning signals: …