Ch. 13 How Populations Evolve Flashcards
Evolutionary Adaptation
An inherited characteristic that enhances an organism’s ability to survive and reproduce in a particular environment
Evolution
Genetic change in a population or species over generations; all the changes that transform life on earth; the heritable changes that have produced Earth’s diversity of organisms
What was Darwin’s main idea?
Species change overtime and living species have arisen from earlier forms
Fossils
A preserved remnant or impression of an organism that lived in the past
What did Darwin write?
“On the Origin of Species by Means of Natural Selection”
How does petrification/fossil develop?
Minderals dissolved in ground water, seep into tissues of a dead organism and replaces the organic matter
Fossile Record
The chronicle of evolution over millions of years of geological time engraved in the order in which fossils appear in rock strata
- position in strata = age
Biogeography
The geological distribution of species
- historical contest of evolution
Comparative Anatomy
The comparison of body structures in different species
- anatomical similarities = common descent
Homologous structure
Structures that are similar in different species of common ancestry
What does “Evolution is a remodeling process” mean?
Ancestral structures originally function in one capacity are modified with new functions
- descent with modification
Comparative Embryology
The study of structures that appear during the development of different organisms
- closely related = similar stages in embryonic development
Molecular Biology
The study of molecular basis of gene and gene expression
- universality of genetic code
What are 4 evidence that validates the evolutionary view of life?
1) Biogeography
2) Comparative anatomy
3) Comparative embryology
4) Molecular biology
5) Fossils
How does population affect natural selection?
All species tend to produce excessive # of offspring, so natural resources are limited and there is a struggle to survive
Natural Selection
Differential success in reproduction by different phenotypes resulting from interactions with the environment; evolution occurs when natural selection produces change in relative frequencies of alleles in a population’s gene pool
- gradual change in characteristics of population (Favored accumulates)
- screens variation
Nature determines which organisms live/die
- depends on adaptations
- survival of the fitness
Artificial selection
Selective breeding of domesticated plants/animals to promote the occurrence of desirable inherited traits in offspring
- modifying species
- over short time
Man determines who lives/dies
- selective breeding and could explain earth’s diversity
What accounts for evolution of new species?
Heritable changes gradually accumulate
Theory of Evolution
Developed to explain the changes of organisms through time
- how organisms of past become organisms of today
Why was there a belief of “species are fixed and unchanging”?
Religion and short lifespan –> no observation or explanation
Who was Jean Baptiste Lamarck
First to oppose to species are not fond yet that changed.
- Law of Use and Disuse (muscles only)
- Law of inheritance of acquired characteristics
What are Charles Darwin’s 5 assumptions?
1) There are more organisms born than can possibly survive
2) Limited amount of resources available
3) Variations exist among members of a species (differences)
4) Organisms with favorable variations to environment are well adapted and survive
5) These organisms mate and pass variation to offspring
Do humans obey natural selection?
No
Populations
A group of individuals of the same species living in same geographic area
- smallest units that can evolve
- problem solutions: adapt, move, die
- change gradually over successive generations based on how adapted
Population Genetics
Science of genetic changes in populations and of microevolutionary changes
- how populations of species evolve
- predicts how/when many of the traits will appear
- frequency of alleles changes with environment
Gene Pool
Total collection of all genes in population at any one time
Microevolution
Small changes in the gene pool over a number of generations
Hardy-Weinberg Equilibrium
The shuffling of genes that occur during reproduction is not enough to change the genetic make up of populations
1) p+ q = 1
2) p^2 + 2pg + q^2
3) Gene frequency tend to remain constant b/w generations provided there is…
- mutation, gene flow, gene drift, natural selection, non-random mating
* Rarely met in nature
Mutation
change or error in genetic code that produces new alleles (creates variation)
- beneficial = raw material of evolution
Gene Flow
Migration, movement of individuals in/out of populations
Genetic Drift
Chance, change in gene pool due to change
- only some with small populations (<100)
- bottle neck effect & founder effect
Bottle neck effect
Population size is reduced drastically due to a natural environment
Founder effect
A new area is colonized by a group creates genetic drift
Modern Synthesis
A comprehensive theory of evolution that incorporates genetics and includes most of Darwin’s ideas, focusing on populations as the fundamental units of evolution
Sexual species
A biological species; a group of populations with potential to interbreed and produce fertile offspring
5 Conditions of Hardy-Weinberg Equilibrium?
1) Population is very large
2) Population is isolated (no migrations of individual + allele)
3) Mutations do not alter the gene pool
4) Mating is random
5) All individuals are equal in reproductive success so natural selection doesn’t occur
* rarely ever met
What are the 5 deviations from Hardy-Weinberg Equilibrium?
1) Genetic drift
2) Gene flow
3) Mutation
4) Non random mating
5) Natural selection
Morphs
2+ kinds of individuals/forms of phenotypic characteristic in a population
Polymorphism
The existence of different forms; may pertain to a population in which 2+ morphs are present in readily available frequencies
Cline
A gradation in an inherited trait along a geographical continuum; variation in a population’s phenotypic features that parallels an environmental gradient (variable)
What two random processes generate variation?
1) Mutations
2) Sexual recombination
Heterozygote advantage
Greater reproductive success in heterozygous individuals compared to homozygous
Neutral variation
Genetic variation that provides no apparent selective advantage for some individuals over otehrs
What does “survival of the fitness” mean?
Survival of genes, not individuals or organisms
Fitness
The contribution an individual makes to the gene pool of the next generation, relative to the contribution of other individuals in the population
What does it mean to be the “fittest” organism?
You pass on the greatest # of genes
What are the 3 modes of natural selection?
1) Stabilizing selection
2) Directional selection
3) Diversifying selection
Stabilizing selection
Natural selection that favors intermediate variants by acting against extreme phenotypes
- stable environment that reduces phenotypic variation
Directional selection
Natural selection that acts against the relatively rare individuals at one end of a phenotypic range
- common with environmental changes
Diversifying selection
Natural selection that favors extreme over intermediate phenotypes
How does human activity affect variations in populations? Examples?
Decreasing genetic variation (less opportunity)
- pollution, burning fossil fuel, pesticides, habitat destruction, overheating, introduction of non-native organisms
Examples of natural causes that variation in populations…
Drought, disease, floods, volcanoes, hurricanes
Loss of biodiversity is…
Human activity plus natural causes
What are the conditions of loss of biodiversity?
1) Threatened species
2) Endangered species
3) Extinct
Why are small populations problematic?
There is too few variation.
- no genetic makeup to adapt
- inbreeding
What are solutions to loss of biodiversity?
1) Captive Breeding Program
2) Wildlife Preserves
3) Germ Plasm Bank
4) Changing Human Behavior
