1. Chapter 5: Evolution, Biodiversity & Population Ecology

2. Evolution
genetic change in populations of organisms across generations.
modifications
appearance:

3. Evolution
functioning: beaks in honeycreepers

4. Natural Selection explains the great variety of living organisms.
derives from several premises noticed in nature

5. Natural Selection Premises
constant struggle of organisms to survive and mate
organisms tend to produce more offspring that can survive.
individuals of the same species are not identical
variation

6. Variation genetical differences
environment within which genes are expressed
interaction between genes and environment
Adaptation: trait that promotes success of a species

7. Effects of Natural Selection on Genetic Variation
Mutations: accidental changes in the nucleotide sequence of the DNA
addition
deletion
substitution

8. Sexual Reproduction also Generates Variation
recombination of genes produces a novel combination generating variation
directional selection
stabilizing selection
disruptive selection

9. Directional selection
selection that drives a feature in one direction

10. Stabilizing selection
preserves status quo, no changes

11. Disruptive Selection traits diverge into two or more directions

12. Evidence of Natural Selection
Selective breeding
breeding of domesticated animals and plants
dog and cat breeds
variations of Brassica oleracea
artificial selection

13. Biodiversity Total of all organisms in the area
diversity of species
gene pool
populations
communities
Evolution generates biological diversity
as of :3 amphibians, 1:7 birds and 1:5 mammals is considered endangered or threaten (National Geographic)
Species: organism that is able to reproduce and have viable offspring

14. Speciation: Allopatric & Sympatric
Allopatric: species form due to physical separation
mutations can occur independently
members of different populations don't mate
populations continue diverging through time
single species can generate multiple species through time

15. Separation of Populations
glacial ice sheets during ice ages
change of course of major rivers
rise of mountain ranges
evaporation of major lakes into smaller bodies of water
temperature variation causing migration of plant populations creating new patterns of animal/plant distribution
isolation must remain for thousands of generations
reunion of populations may occur, but if they are not able to interbreed, two or more new species have emerged.

16. Sympatric reproductively isolated due to behavioral causes
feeding at different times of the day
feed at different sites
mating on different times of the year
hybridization in some plants
mutations causing change in number of chromosomes

17. Diversification as a result of numerous speciation events
phylogenetic trees explain differences and similarities between species
Speciation and extinction
natural process that takes 1-10 million years

18. Diversification

19. Species Vulnerable to Extinction
some species may be more vulnerable than others due to change in environmental conditions
climate change
rise and fall of sea level
arrival of harmful species
extreme weather events (drought, flood, etc.)
Endemic: single small population present only in a particular type of environment: Attwater chicken

20. Attwater Chicken 1 million individuals in 1900
50 or so individuals today
habitat disruption
oil industry, housing, cattle, rice
fields
predators (snake, rat, skunk)
diseases
weather
collision (fence, cars)
fire ants (kill chicks)

21. Levels of Ecological Organization
Species
Population
Communities
Ecosystems
Biosphere

22. Ecological Organization

23. Habitat, Niche and Specialization
Habitat: living and non-living elements around a species
thriving of a species depends on patterns of habitat use
each species' habitat is scale dependent
habitat selection is possible if the species is mobile
the survival of the species depends if the habitat is suitable or not

24. Niche
a species' niche reflects its use of resources and functional role in the ecosystem
"job"
specialists and generalists
Prairie dog
eats grasses and keeps grass low for predator control
more grass grown around burrow because
airiates soil by digging
soil becomes richer near burrows because of dung
burrow houses other animals when empty (snakes, rabbits, owls)

25. Population Ecology
Population size: number of individuals present at a given time
Attwater chicken- 1 million to 50 individuals
Population density: number of individuals per population per unit area
golden toad- large population in a small area
Population distribution: spatial arrangement of organisms within an area. There are 3 types.

26. Population Distribution: Random

27. Uniform

28. Clumped

29. Population Ecology
sex ratio: depends on the behavior (monogamous or polygamous) of the species, type of reproduction (autofecundates or different sexes)
age structure: age structure diagrams

30. Population Ecology birth and death rates: survivorship curves
type I: higher mortality at older age
type II: equal rate of death at any age
type III: higher rate of death at younger age
k-selected
r-selected

31. Population Ecology Immigration emigration growth rate
Unregulated population increase: shows exponential growth= J curve
carrying capacity causes logistic growth curve (S curve) to show
caused by an environmental resistance (water, food, shelter, predators, disease)

32. Density-dependent factors
its influence is affected by the population density
competition
food
shelter
mate
water
s-shaped curve

33. Density-independent factors
influence is not affected by population density; can eliminate large numbers of individuals without regard to its density
extreme temperatures
catastrophic climate events
fires
volcano eruptions

34. Biotic Potential vs Reproductive Strategy
k-selected (k stands for Carrying capacity)
low biotic potential
long gestation period
protects offspring as an investment for species survivor
relative few offspring during lifetime
type 1 curve
eg: humans, whale, rhino, elephant

35. r-selected (r stands for rate) focus on quantity not quality
high biotic potential
large number of offspring
survivor of offspring depends on chance
type 3 curve
eg. fish, frogs, snails

36. Conservation of Biodiversity
social and economic factors
human behavior towards environment
economy vs environmental protection
protection of environment
began without much government support
even today governments may not have the funds
ecotourism is the key
THE END