Biol 418 Evolutionary Ecology

Transcription

1 Biol 418 Evolutionary Ecology 1

2 INSTRUCTOR Office: BioSciences 1370 Office Hours:???? (or by appointment) TEACHING ASSISTANT Kerry Marchinko Office: BioSciences???? Office Hours:???? Structure & Philosophy Aim To describe the workings of selection in wild populations, the ecology that drives it, the processes that constrain it and the evolution that results. To encourage you to realise that science is better seen as a process than as a body of fact. To encourage you to think critically about the (natural) world and to present ideas clearly and concisely. Lectures: Tutorials: Essays: I tell you things Connect with primary literature You tell me (& each other) things Explore lecture topic and discuss journal articles Contact with primary literature Practice in discussion and criticism Write clearly and concisely Order thoughts into sensible arguments 2

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4 Literature Lectures and tutorials connect with primary literature Encourage you to do the same in essays and exam Helps critical thinking! The main journals relevant to include: Specialised: American Naturalist Ecology Ecology Letters Evolution Journal of Animal Ecology Journal of Evolutionary Biology Molecular Ecology Proceedings of the Royal Society, B Trends in Ecology and Evolution (for reviews) General: Proceedings of the National Academy of Science Nature Science 4

5 Assessment DISTRIBUTION OF MARKS Tutorials 10% Essays 50% Final exam 40% GRADING PRACTICES Late submission of assignments will not be accepted without good reason: Students who miss tutorials or essays because of short-term medical, emotional or other problems should contact the instructor as soon as possible to arrange a schedule for catching up. In long-term cases students should request Academic Concession as soon as possible. Students who miss the final examination because of medical, emotional or other problems should follow the procedures for requesting Academic Concession as soon as possible. What is evolutionary ecology? Roughgarden, 1979: the fusion of population ecology with evolutionary theory. Lack, 1965: concerned with those problems of numbers, distribution and other ecology of plants and animals for which the explanation must be sought in the evolutionary history of the species. Cockburn, 1991: explores the role that evolution plays in ecology. Schluter (pers. comm.): study of the ecological causes and consequences of evolutionary change, past and present. 5

6 What is evolutionary ecology? Ecology Evolution Individuals Populations Communities Ecosystems Anagenesis (lineage change through time) Cladogenesis (lineage splitting) A branch of evolutionary biology concerned mainly with contemporary natural populations and emphasising the study of process and mechanism as well as pattern and outcome. 6

7 Sex ratio in humans STATEMENT: Human male and female offspring are produced in a 1:1 sex ratio Sex ratio in humans STATEMENT: Pergament et al Reproductive Biomedicine Online 5: Human male and female offspring are produced in a 1:1 sex ratio In fact, the sex ratio varies both in time and space, with more males generally being conceived than females 7

8 Sex ratio in humans STATEMENT: Pergament et al Reproductive Biomedicine Online 5: Human male and female offspring are produced in a 1:1 sex ratio In fact, the sex ratio varies both in time and space, with more males generally being conceived than females WHY? Many environmental, physiological and genetic factors may play a role e.g. hormone concentrations, stress, pollutants, age, diet. Stress and sex ratio in humans Catalano et al. (2006) Human Reproduction 21: Fukuda et al. (1998) Human Reproduction 13: Hansen et al. (1999) BMJ 319: Surveys show a drop in the ratio of males to females that are conceived during catastrophic events associated with acute stress e.g.: Natural disasters: earthquakes, floods (Fukuda et al. 1998) Man made disasters: war, terrorist attacks (Catalano et al. 2006) Personal disaster: death or catastrophic illness (Hansen et al. 1999) 8

9 Stress and sex ratio in humans Obel et al. (2007) Human Reproduction 22: Recent survey showed a drop in the ratio of males to females that are conceived during chronic stress (Obel et al. 2007) pregnancies and births followed in Denmark between 1989 and 1992 The more stressed the mother had been during pregnancy, the lower the chance of her giving birth to a boy: 47 % of births by the 25 % most stressed mothers were boys. 52 % of births by the undistressed group were boys. Stress and sex ratio in humans Stress seems to bring about a reduced ratio of males to females Could this trend be an evolutionary response? If so, what possible adaptive mechanisms could explain it? 9

10 Keep in mind. Evolution is a contemporary process Evolutionary time can be synonymous with ecological time Evolution can be observed in a human s lifetime Many processes in nature (e.g. sex ratio) we take for granted maybe moulded by environmental selection pressures A goal of this course is to identify such environmental selection pressures and their evolutionary consequences. 10