CH 22: darwinian evolution

charles darwin

published hypotheses in The Origin of Species in nov 22, 1859, focused on diversity of organisms

descendants of ancestral species

descent with modification aka evolution

micropopulation

change in allele frequencies of population over time

population

group of organisms that belong to the same species and live in the same area

Linnaeus

swedish botanist, noted remarkable match between organisms and environment bc evidence of design by a Creator, developed binomial nomenclature and classification hierarchy

Hutton

scottish geologist, earth’s geological features are the result of gradual mechanisms like erosion can form canyons but it requires lengthy periods of time (he thought 6000 yrs)

Malthus

published “an essay of the principle of population” on human populations, population growth was exponential, resource availability is linear, resource is limited and consequence is competition, noted the potential for human population to increase faster than food supplies

Lamarck

french biologist, published two principles in 1809, use and disuse, inheritance of acquired characteristics, giraffe necks stretching and passes on to offspring, is there genetic basis?

Cuvier

developed paleontology (study fossils), observed that older the strata (earth’s layers), the more dissimilar the fossils to current life, speculated that boundaries represented sudden events, opposed idea of evolution

Lyell

wrote and published principles of geology, not convinced about evolution, encouraged Darwin to publish ideas

adaptation

inherited characteristics of organisms that enhance their survival and reproduction in a specific environment

Darwin’s past

liked nature, studied medicine and didn’t like it, then theology at Cambridge, took on around the world voyage on HMS Beagle w Captain R. FitzRoy to chart South American coastline

voyage of the Beagle

Darwin collected specimens of south american plants and animals, observed fossil resembled living species from same region and living species resembled other species from nearby regions

natural selection

mechanism of descent with modification, process in which individuals with favorable inherited traits are more likely to survive and reproduce

Darwin explained three observations

unity of life, diversity of life, ways organisms are suited to life in their environments

selective breeding

process Darwin called artificial selection, selecting individuals with desired traits

Darwin drew two inferences from two observations, observations:

1. members of a population often vary in their inherited traits

2. all species can produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce

Darwin drew two inferences from two observations, inferences:

1. individuals whose inherited traits give them a higher likeliness of surviving and reproducing in a given environment tend to leave more offspring than other individuals

2. this unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations

key features of natural selection

1. individuals with certain heritable traits survive and reproduce at a higher rate than others

2. natural selection increases frequency of adaptations that are favorable in environment

3. if environment changes over time, natural selection may result in adaptation to these new conditions and birth new species

4. can only increase or decrease heritable traits

individuals do not evolve

populations evolve

data documenting the pattern of evolution

1. direct observations'

2. homology (similarities between two organisms due to shared ancestry)

3. fossil record

4. biogeography

two examples provide evidence for natural selection

1. natural selection in response to introduced species

2. evolution of drug-resistant bacteria

homology

similarity resulting from common ancestry

homologous

same origin, different function

analogous

different origin, same function

vestigial structures

remnants of features that served a function in the organism’s ancestors

evolutionary trees

diagrams that reflect hypotheses about relationships among different groups, can be made using different types of data

convergent evolution

evolution of similar (or analogous) features in distantly related groups, does not provide info about ancestry,

endemic species

species that are not found anywhere else in world, islands have many of them that are often closely related to species on nearest mainland/island