Biology 104 - Exam 1 Flashcards Preview

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Flashcards in Biology 104 - Exam 1 Deck (45):
1

biodiversity

how many different organisms are on the planet

2

evolution

- change overtime, descent with modification
- change in allele frequencies between generations of a given population

3

microevolution

short-term genetic changes within a population of species

4

fossils

preserved remnants, impressions in rock of once living organisms

5

fitness

individual reproductive contribution to the next generation

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directional selection

an extreme phenotype is fittest and shifts the phenotype curve

7

disruptive selection

leads to a balance between 2 or more contrasting phenotypes in a population

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stabilizing selection

maintains variation for a particular trait with a narrow range

9

heterozygote advantage

harmful alleles in one way confer benefit in another
- i.e. heterozygotes for sickle cell are immune to malaria and don't necessarily have the disease

10

mutations

- DNA randomly changes to introduce new alleles
- increases genetic diversity
- affect evolution on in subsequent generations that inherit the mutation

11

genetic drift

- changes in the gene pool due to chance
- rooted in sampling error and has strong affect on small populations
- founder effect & bottleneck effect

12

founder effect

- founders of a new population
- bring only their alleles => reduces diversity
- entire genotypes eliminated
- rare traits may increase in frequency

13

bottleneck effect

- population drastically reduced in size
- over hunting, natural disaster, habitat loss
- typically reduces genetic diversity in the surviving population

14

paleontology

the study of fossils to understand historical ecology, evolution, and human relevance to the past

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relative dating

looking at fossils above and below to determine age => estimation

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absolute/radiometric dating

- approximates fossils/sediment age using radioactive isotopes

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half-life

the time it takes for half the isotope to lose half of it's mass

18

biogeography

study of the distributions of species on the planet

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homologous structures

structures inherited from a common ancestor

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vestigial structures

homologous structure that no longer has a function in a species

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analogous structure

structure is alike but there is no common ancestor
- also known as convergent evolution
- selective pressures lead to similar adaptations but not because of commonality

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Hardy-Weinburg equilibrium

1. no natural selection
2. no mutations
3. large population
4. individuals mate at random
5. no immigration OR emmigration

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homeotic genes

genes that control development (evo-devo)
- small differences in expression of genes can lead to a new body plan

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macroevolution

major changes in the history of life that occur over long periods of time

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species

a population or group of populations whose members can interbreed and produce viable offspring

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reproductive isolation

leads to speciation, formation of a new species

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Issues with Linnaeus' theory of species

1. cannot apply to asexually reproducing organisms
2. impossible to assign species names to organisms known only as fossils
3. some organisms interbreed in captivity but not in nature
4. reproductive isolation is not absolute - interbreeding is still possible despite isolation

28

prezygotic reproductive barriers

occur before the formation of the zygote
- prevents mating
- prevents fertilization if mating is attempted
- i.e. habitat, temporal, behavioral, mechanic, gametic

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postzygotic reproductive barriers

if the zygote is formed:
- failure to develop/reach sexual maturity
- failure to produce gametes
- feeble or sterile offspring
- i.e. hybrid inviability (don't reach maturity), hybrid infertility (infertile), hybrid breakdown (not able to reproduce)

30

allopatric speciation

no contact between populations
- physical barrier separates the populations

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sympatric speciation

continuous contact between populations
- populations share a habitat but diverge anyway

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gradualism

start with a common ancestor and changes slowly appear

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punctuated equilibrium

direct, blunt changes in the species
- long periods of limited change interrupted by bouts of rapid change

34

rapid speciation occurs

- with evolution of key adaptation
- as consequence of widespread extinction event

35

extinction

species is extinct when all members have died
- failure to adapt to environmental changes
- i.e. habitat, new predator, new disease

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background extinction rate

- gradual loss of species to extinction
- 0.1 to 1.0 per year per one million species

37

impact theory

suggests that meteorites and comets crashed to the Earth and changed the atmosphere/environmental conditions
- i.e. extinction of dinosaurs

38

plate tectonics

shifting of the continents

39

human impact

thought to be causing the 6th mass extinction
- losing estimated 20 to 200 per year per one million species

40

systematics

study of classification

41

taxonomy

the science of describing, naming and classifying species
- the more features shared by two species, the more taxonomic levels they share

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phylogenics

study of evolutionary relationships among species

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phylogenic trees

depict evolutionary relationships based on descent from common ancestors
- multiple lines of evidence used to construct the trees

44

clade

group of organisms consisting of a common ancestor & its descendents

45

cladogram

type of phylogenic tree
- built using ancestral and derived characters
- makes use of homology