Non-random mating patterns and consistency of behaviour of amphibians

Ing. Petr Chajma

Doctoral thesis

Abstract:

Non-random mating patterns are frequently studied topic. However, the studies suffer from many misconceptions, built upon poor understanding of statistical methods. Most attention was given to the patterns based on size, such as size-assortative mating, size-disproportionate mating and size-dependent mating. In this thesis, I present the results of our study, describing the presence (and absence) of such non-random mating patterns in two explosively breeding anurans – the common frog (Rana temporaria) and the common toad (Bufo bufo) (Chapter 1), and examined the mechanics of physical mating constraints in pair formation, as one of the causes of these patterns (Chapter 2). Our findings showed that size may not be the most important trait in mate acquisition, as more active males had higher chances of acquiring mate, even if they were not exactly a match in terms of body size. Intrigued by these results, we tried to see, if the assortment by size can at least enhance individual fitness by improving egg fertilization success (Chapter 3), as expected by other authors. Fertilisation rate of common toads did not depend on the size difference of mates, giving another crack to the commonly accepted theory.Next, we tried to build on the notion that male activity is important part of their mating pattern and tested, whether the activity and other behavioural traits are consistent, and can therefore be subjected to the selective pressure (Chapters 4 and 5). Although activity was not consistent in smooth newt (Lissotriton vulgaris), exploration and boldness were consistent in this species, showing the potential of behavioural traits in mate acquisition (Chapter 4). However, the question of heritability of such traits was still unanswered. We tried to shed some light on it by comparing behavioural traits and their consistency between siblings of common frog tadpoles, while addressing the potential changes in consistency caused by different population densities in early development of common frog tadpoles (Chapter 5). Although population density had a significant effect on tadpole behaviour, individuals showed consistency only in their boldness, not in activity and exploration. Furthermore, there was no consistency in the behaviour of siblings, which does not speak well about heritability of those traits.Reviewing studies of other authors, I conclude that non-random mating patterns based on size are rare in amphibians and their influence is overestimated due to the incorrect interpretation of published results. The role of behaviour traits in amphibian mating patterns is still yet to be examined, but the proof of their heritability should be presented, before considering their evolutionary meaning.

Abstract:

Non-random mating patterns are frequently studied topic. However, the studies suffer from many misconceptions, built upon poor understanding of statistical methods. Most attention was given to the patterns based on size, such as size-assortative mating, size-disproportionate mating and size-dependent mating. In this thesis, I present the results of our study, describing the presence (and absence) of such non-random mating patterns in two explosively breeding anurans – the common frog (Rana temporaria) and the common toad (Bufo bufo) (Chapter 1), and examined the mechanics of physical mating constraints in pair formation, as one of the causes of these patterns (Chapter 2). Our findings showed that size may not be the most important trait in mate acquisition, as more active males had higher chances of acquiring mate, even if they were not exactly a match in terms of body size. Intrigued by these results, we tried to see, if the assortment by size can at least enhance individual fitness by improving egg fertilization success (Chapter 3), as expected by other authors. Fertilisation rate of common toads did not depend on the size difference of mates, giving another crack to the commonly accepted theory.Next, we tried to build on the notion that male activity is important part of their mating pattern and tested, whether the activity and other behavioural traits are consistent, and can therefore be subjected to the selective pressure (Chapters 4 and 5). Although activity was not consistent in smooth newt (Lissotriton vulgaris), exploration and boldness were consistent in this species, showing the potential of behavioural traits in mate acquisition (Chapter 4). However, the question of heritability of such traits was still unanswered. We tried to shed some light on it by comparing behavioural traits and their consistency between siblings of common frog tadpoles, while addressing the potential changes in consistency caused by different population densities in early development of common frog tadpoles (Chapter 5). Although population density had a significant effect on tadpole behaviour, individuals showed consistency only in their boldness, not in activity and exploration. Furthermore, there was no consistency in the behaviour of siblings, which does not speak well about heritability of those traits.Reviewing studies of other authors, I conclude that non-random mating patterns based on size are rare in amphibians and their influence is overestimated due to the incorrect interpretation of published results. The role of behaviour traits in amphibian mating patterns is still yet to be examined, but the proof of their heritability should be presented, before considering their evolutionary meaning.

Keywords

Size dependent mating, Behavioural consistency, Size assortative mating, Behavioural syndrome, Temperament

Keywords

Size assortative mating, Size dependent mating, Behavioural consistency, Behavioural syndrome, Temperament

Language used: Czech

Date on which the thesis was submitted / produced: 2. 9. 2020

Thesis defence

• Supervisor: doc. Ing. Jiří Vojar, Ph.D.
• Reader: Ivan Rehák, externi, Martin Rulík, externi, Peter Mikulíček, externi

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Doctoral programme / field:
Ecology / Ecology