BIO120H1 Lecture Notes - Lecture 12: Biodiversity Hotspot, Phylogenetic Diversity, Insular Biogeography

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12 Jul 2017
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BIO120: Biodiversity, Extinction, and Conservation Biology (Lecture 12)
E.O. Wilson
-Harvard
-responsible for getting us to be concerned about loss of biodiversity
-entomologist, works on ants
-originated one of most important theories: theory of biogeography
Amazon Tropical Forest
-logging
-clearing forests for grazing
-erosion becomes a problem
-now you see mostly soya beans and crops
Ontario
-trillium: nothing known about genetics or reproductive biology
-problems with studying: population shrinking due to urban development
-what are the demographic and genetic consequences of these small populations?
Today’s Global Environmental Problems
-global warming and climate change
-loss of biodiversity
-environmental pollution
-human famine
-spread of infectious diseases
-human population growth
-demography of humans, carrying capacity (Malthus)
running out of resources
How Will Organisms Respond to Climate Change?
-migrate to more favourable environmental conditions (ecology)
what’s going to happen to species in Indian and Pacific oceans inhabiting low level
islands that will be flooded in 50-100 years, where will they go?
plants that occur on mountains: can move up to track cooler conditions, but what
happens when you get to the top?
-adapt to changing environmental conditions (evolution)
-go locally (or globally) extinct (evolution)
local extinction: extirpation
Climate Change Alters Phenology
-how much of this response is evolution?
-these are all long terms studies where people have censused populations over years,
people looking at various aspects of population biology (when do they lay eggs, when do
they appear in the season, when do they flower)
-fitted regression lines, in all cases there is a change happening
days to flowering getting shorter, flowering earlier in season
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emerging earlier, laying more eggs, laying dates of first eggs earlier
-phenotypic response: is this heritable (genetic), is this evolution or just plasticity
Can Drought Cause Rapid Contemporary Evolution by Natural Selection
-Art Weis
-experiment: studied plants in same location in wet and dry year, observed over years
-annual plants live under a year, germinate when rains come
challenge is to germinate seeds before drought comes
-directional selection on flowering time:
evidence for directional selection for early flowering in both populations in 2002
earlier flowering plants set more seed than later flowering plants
-resurrection paradigm: seeds collected in 1997 and 2004 and compared
before and after selection (serious drought during this period)
grew seeds in common garden greenhouse situation, crossed them to see heritability
(quantitative trait?)
-evolutionary response to drought involves selection for earlier flowering in both
populations
one population: 2 days earlier in 2004
another population: 8 days earlier
hybrids intermediate
-note field mustard has an annual life cycle; such responses would take a lot longer in
perennials
some take decades/centuries before they flower (forest species)
Biodiversity
-the variety of life on earth
-the number and kinds of living organisms in a given area
-two elements:
1. interspecific variation or species diversity (studied by ecologists)
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