AP Bio test unit 7

Mass extinction

permanent loss of major groups of organisms

Aristotle

Naturalist, Aristotle did not believe in the evolution of species, instead proposing that species are eternal, fixed, and unchanging. Believed that all species were created in a perfect state so they didn’t need to change over time

Georges Cuvier

naturalist: ; Cuvier proposed Catastrophism, arguing that Earth's history was marked by sudden, violent catastrophes that wiped out species, which were then replaced by new, unrelated species from other areas, rather than by gradual evolution

Important people who influenced Darwin’s theory on evolution

• Charles Lyell (Geology)

• Thomas Malthus (Population Dynamics):

• Alfred Russel Wallace (Co-discoverer): Wallace sent Darwin a paper outlining a very similar theory of natural selection based on his own studies in the Malay Archipelago, which motivated Darwin to publish On the Origin of Species in 1859

• Jean-Baptiste Lamarck (Early Evolutionist):

Jean-Baptiste Lamarck

one of the first scientists to propose that species change over time. He thought environmental pressures cause an internal need for change in an indiciduals body and this change is inherited by offspring.

Charles Lyell (Geology)

Thomas Malthus (Population Dynamics):

Lyell’s Principles of Geology promoted "uniformitarianism," arguing that slow, gradual changes (like erosion) built up over time to shape the Earth, rather than sudden catastrophes. Darwin applied this gradualism to biology.

Malthus argued that human populations grow faster than resources (food), leading to famine and disease. Darwin applied this idea to animals and plants, concluding that only those with advantageous traits survive the struggle for resources.

Evolution

the change in genetic makeup of a population over time. driven by random occurences like natural selection, mutation, genetic drift, and gene flow.

Natural selection

Major driver for evolution. it’s the process in which organisms that have adaptations better suited for the environment have a greater chance of survival and reproduction, alllowing adaptations to pass on to future gens.

natural selection conditions

there must be competition for limited resources, variation in the population (diff pheotypes), reproductive success, and heritability of traits

fitness

the ability of an organism to survive and produce fertile offspring. both reproductive fitness and hereditability contribute to this.

heritability

ability to pass on adaptations to future genrations. selection causes those who have reproductive success to have their traits most common in the pop

Ecosystem stability

determines the rate of and direction of evolution. environments can experience major disruptions and change quickly overtime or slowly
stable environment=not likely to evolve
unstable environment: increased rate of evolution as species adapt to change in environment

variation

genetic differeneces among organisms within a population
more variation = more fitness. variation can be on a cellular or molecular level
Ex: cholophyll molecules within a plant: Different chlorophyll molecules exist to absorb different light wavelengths, enhancing photosynthesis.
-Adults typically produce Hemoglobin A, while fetuses produce Hemoglobin F, a different protein structure adapted for extracting oxygen from the mother's blood.

Artificial selection

process by which humans select desirable traints in other species and selectively breed these individuals with desired traits to get the desired offspring. can be bread for physical or behavioral characteristics. Good examples are every single domestic dog breed we have that came from one species: wolves. Another is a wild cabbage plant that was bread to make broccoli, green cabbage, brussel sprouts, kale, etc.

genetic drift

the random change in the frequency of a particular allele within a popilation. it is a NONSELECTIVE process that occurs in SMALL POPULATIONS usually.

includes bottle neck events and natural catastrophes, founder effect

bottle neck event

when a large diverse population is suddenly reduced to a small population

founder effect

random process that reduces genetic variation within a small population due to a separation from the larger population. (due to migration or geological events that caused isolation from the population. genetic makeup of a founder population can be different from the original one since a few individuals are repopulating the lost individuals from the original pop.

Gene flow

movement of individuals between populations causing an exchange of alleles between populations (ex is migration)
-introduces new genes into populations which increases genetic variation, however, continued migration can decrease genetic diversity over time.

Hardy-wienburg

model for describing and predicting allele frequencies in a non-evolving population.
equations: p+q=1 and p²+2pq+q² (can be used to find phenotype or genotype frequencies)

hardy-weinburg equilibrium

5 conditions:
-must be a large population
-random mating so no sexual selection
-no net mutations: no deletions or duplications or modifications
-no gene flow/no migration
-no natural selection
provides good null hypothesis, in this equilibrium frequencies of alleles and genotypes are always the same

what do p and q mean in the equation p+q=1 what do p² and q² mean in the other eq?

they stand for the frequency of ALLELES. p is the dominant allele frequency and q is the recessive.
p² is the frequency for homozygous DOMINANT. q² is homozygous RECESSIVE.

types of evidence for evolution

geographical evidence(habitat, land area), geological evidence(fossils, environmental features of the earth over time), mathmetical evidence, physical(phenotypes of species), and biochemical(comparing sequences of DNA and proteins)

Morphological homologies

structural similarities between different species, such as bone arrangements, derived from a common ancestor
-homologous structures

homologous structures

physical features that look similar in different species that share a common evolutionary ancestor and serve different functions. DIVERGENT EVOLUTION, structures evolve to serve a different function. (e.g., human arm/whale flipper).

analogous structures

evolved independently in diff species due to similar environmental conditions/selective pressures
CONVERGENT EVOLUTION: independent evolution of similar features in species of different lineages, driven by similar environmental pressures rather than shared ancestry.

(e.g., wing of a bat and wing of a bird)

stuff all organisms have that proves they’re related