Biol 1020 Exam 4 ch. 23-Ecology

Hardy-Weinberg theorem

p²+2pq+q²

In the Hardy-Weinberg Theorem p represents

frequency of dominate allele

In the Hardy-Weinberg Theorem q represents

frequency of occurrence of recessive allele

In the Hardy-Weinberg Theorem p² represents

frequency of homozygous dominant genotypes

In the Hardy-Weinberg Theorem 2pq represents

frequency of heterozygous genotype

In the Hardy-Weinberg Theorem q² represents

frequency of homozygous recessive genotypes

What are the assumptions of the Hardy-Weinberg Equilibrium

• large population size

• no migration or gene flow

• no mutations

• random mating

• no natural selection

Genetic drift

change in gene frequencies of populations due to small population size

Gene flow

caused by migrating individuals carrying their allele with them and usually results in changes in allele frequencies

Fitness

relative ability of a genotype to contribute to future generations

Directional selection

species adapt to environmental change by favoring selection of one extreme over the other

Stabilizing selection

When populations are well adapted to their environments, selecting against phenotypic extremes

Disruptive selection

when more than one extreme phenotype is favored over intermediate phenotypes

Macroevolution

formation of new species and the accompanying events

Species biological concept

one or more populations whose members are capable of interbreeding, able to reproduce fertile offspring, and reproductively isolated from other such groups

reproductive isolation

mechanism that prevents gene flow between two species

Prezygotic barriers

prevent fertilization (zygote formation) between gametes from two species

Postzygotic barriers

reproductive isolation after fertilization has occurred

Habitat isolation

Form of prezygotic barrier; similar species reproduce in different habitats

Temporal isolation

Form of prezygotic barrier; similar species reproduce at different times

Behavioral isolation

Form of prezygotic barrier; similar species have distinctive courtship behaviors

Mechanical isolation

Form of prezygotic barrier; similar species have structural differences in their reproductive organs

Gametic isolation

Form of prezygotic barrier; Gametes of similar species are chemically incompatible

Hybrid inviability

Form of postzygotic barrier; interspecific hybrid dies at early stage of embryonic development

Hybrid sterility

Form of postzygotic barrier; Interspecific hybrid survies to adulthood but is unable to reproduce successfully

Ex: mule

Hybrid breakdown

Form of postzygotic barrier; offspring of interspecific hybrid have problems reproducing

anagenic speciation

gradual change of one species not a new form with the new form replacing the old form

cladogenic speciation

when two or more species are present where only one had existed before; species share a common ancestor

Allopatric speciation

one population becomes geographically separated from the rest of the species

sympatric speciation

a species becomes reproductively isolated and evolves in the same geographic location as ancestral species

Adaptive radiation

the rapid production of many species from a common ancestor

Darwin’s Gradualism Model

suggests that evolution occurs gradually

Punctuated equilibrium

Evolution occurs quickly compared to gradual

How old is the earth?

4.6 billion years old

Earth’s early atmosphere was lacking in what gas

O2

What are the four requirements for forming life on Earth

1) little or no free oxygen

2) abundant energy sources

3) Chemical building blocks of water, dissolved mineral ions, and atmospheric gases

4) time

Polymers

spontaneous formations from monomer building blocks on sand, clay, or rock surfaces

Prebiotic broth hypothesis for how life on Earth began

life began from an ‘organic soup’ in the oceans

bubble hypothesis for how life on Earth began

‘oily bubbles’ from an organic soup interacted with land surfaces at shallow seas or seashores

iron-sulfur world hypothesis for how life on Earth began

life began from an ‘organic soup’ interacting with mineral surfaces at hyper thermal vents in the ocean floor; with abundant iron and sulfur there impacting the early metabolism that developed

deep-hot biosphere hypothesis for how life on Earth began

life began in an ‘organic soup’ deep within the earth

exogenesis explanation for how life on Earth began

an extraterrestrial source put life on Earth

RNA world hypothesis

RNA is believed to be the component of the first cells with DNA coming along later

In vitro evolution

How RNA has evolved and this supports the RNA world hypothesis

microfossils of prokaryotic cells

first evidence of cells

Stromatolites

rocklike structures made up of layers of bacteria and sediment

The first cells were likely…

anaerobic heterotrophs

The first photosynthetic organisms were likely…

Cyanobacteria

Stromatolites containing cyanobacteria have been found to date as far back as

3.5 bya

Banded iron formations

date back about 2.5 by a and indicate the massive release of O2 into the oceans

About how long ago did eukaryotes first appear in the fossil record

2 bya

Precambrian time

from 4.6 by a to 542 million years ago; possibly a snowball earth and ended with the Ediacaran Period

Paleozoic Era

542-251 mya; contains the Cambrian period, Ordovician period, Silurian period, Devonian period, Carboniferous period, Permian period

Ended with the largest mass extinction event

Cambrian period

542-488 mya; Biggest expansion in diversity with the Cambrian explosion of multicellular organisms

Ordovician period

488-444 mya; species include trilobites, brachiopods, mollusks; first coral reefs and terrestrial plants

Ended with the first mass extinction event that was likely due to an ice age

Silurian period

444-416 mya; first vascular plants and first true terrestrial animals

Devonian period

416-359 mya; Age of fishes with jawed fishes diversifying and dominating seas; amphibians and insects first appear & vascular plants diversify

Ended with 2nd mass extinction event

Carboniferous period

359-299 mya; reptiles appear and amphibians diversify and dominate terrestrial carnivores making this the age of amphibians

Permian period

299-251 mya; by the end of this period the continents have merged as the Pangaea super continent

Ended with the 3rd mass extinction event

Mesozoic era

251-65 mya; age of reptiles/ dinosaurs

contains the triassic, jurassic, and cretaceous periods

Triassic period

251-200 mya

dinosaurs and mammals first appear; gymnosperms are dominant land plants

Ended with the 4th mass extinction event that paved the way for dinosaurs

Jurassic period

200-146 mya

Dinosaurs dominate the land and birds evolve from dinosaurs

Cretaceous period

146-65 mya

Flowering plants evolved and diversified; many animals coevolved with flowering plants

Ended with 5th mass extinction event that killed the dinosaurs and gymnosperms

Iridium layers worldwide, deposits from tsunamis around the Gulf of Mexico, and a large crater site in the Yucatan Peninsula of Mexico provide evidence for…

the 5th mass extinction being caused by impact of a large extraterrestrial body

Cenozoic Era

65 mya - present

Age of Mammals along with diversification of birds, insects, and flowering plants

Contains the Paleogene and neogene periods

Neogene period

The rise of humans

Has many ice ages and mass extinctions and will result in the 6th mass extinction

Ecology

Scientific study of interactions between organisms and the environment

Biotic factors

living organisms that shape the environment

Ex: aquatic plants and fish

Abiotic factors

Non-living components of the ecosystem that shape the environment

Ex: mountain

Climate

long term prevailing weather conditions at a given place

Abiotic factors of climate

land formations and bodies of water (by heating and cooling air masses)

How do mountains effect climate

influence air flow and the amount of sunlight that reaches an area & the higher the elevation the more cold and less oxygen available

Equinox

start of spring and fall

Solstice

start of summer and winter

biomes

classified by the species that live in a certain area (major life zones)

What causes the seasons

tilt of the earth

Lakes

One of the major aquatic biomes; standing fresh water with littoral (shallow) and limnetic (deeper) zones

Wetlands

One of the major aquatic biomes; water-saturated soil and sometimes standing water

Streams & rivers

One of the major aquatic biomes; fresh water with a current

Estuaries

One of the major aquatic biomes; river/sea transition, salt/fresh water content varies, influenced by tide and slow flow of water

Intertidal zone

One of the major aquatic biomes; exposed and covered up daily by the tides

Ocean pelagic zone

One of the major aquatic biomes; open ocean with currents and deep photic zone

Coral reefs

One of the major aquatic biomes; photic zone with calcium carbonate substrate, very diverse

Marine benthic zone

One of the major aquatic biomes; the sea floor

photic zone

zone of water biome where light reaches

aphotic zone

zone of water biome where no light reaches

benthic zone

bottom of water biome

Turnover in lakes

Process driven by temperature changes when nutrient-rich bottom waters turnover with oxygen-rich top waters

Help keep life alive by keeping the entire lake oxygenated

Eutrophication

nutrient-rich water has algal blooms and then lots of detritus; both deplete oxygen

Tropical forest

One of the major terrestrial biomes; rainy with thick forest/closed canopy, diverse

Desert

One of the major terrestrial biomes; monsoons, fluctuates between tempurature extremes, scattered vegetation, dry

mostly near 30 degrees latitude

Savanna

One of the major terrestrial biomes; warm all year, wet and dry seasons, grasses scattered with thorny trees, has adaptations to fire and dryness

chaparral

One of the major terrestrial biomes; near coast, cool and wet winters, long dry summers, shrubs and small trees, fire-adapted

temperate grassland

One of the major terrestrial biomes: dry, cold winter; wet, hot summer; grass-dominated; where most of human food is grown

Taiga (coniferous forest)

One of the major terrestrial biomes: largest biome; cold, long winters; conical trees (snow adaptation)

temperate broadleaf forest

One of the major terrestrial biomes: winters near freezing; hot, humid summers; moderate to high rainfall; vertical flora layers

Tundra

One of the major terrestrial biomes: high wind; long, cold winters; short, cool summers; permafrost; moss, lichens, some grasses, dwarf trees

Makes up 20% of land

Climograph

graph of temperature vs. precipitation

Ecotone

biome transition zone

Population ecology

study of populations in relation to their environment