Biology 2 Chapter 20 Terms & Concepts

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macroevolution

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the evolutionary change that produce new species and new groups of species; occurring over long periods of time

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species

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group of organisms that maintains a distinctive set of attributes in nature

there's much difficulty in differentiation and identification because of subspecies and ecotypes

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ecotypes

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genetically distinct population of a species adapted to its local environment

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subspecies

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two or more geographically restricted groups of the same species display one or more traits that are different but it isn't enough to be completely different species

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speciation

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the mechanisms that promote the formation of new species

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morphological identification of a species

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looking at phenotypes

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problems of using morphological identification of a species

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how to tell what level of dissimilarity will deem a new species

some species can look entirely different but are still the same and some look the same and aren't

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reproductive isolation

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prevents one species from successfully interbreeding with another species

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reproductive isolation identification of a species

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if they can't mate then they aren't the same species

must be viable and fertile offspring

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problems of reproductive isolation identification of a species

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difficult to determine in nature

some species can interbreed and yet do not

doesn't apply to asexual species

can't be applied to extinct species

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molecular identification of a species

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involves comparing of DNA sequences within genes, gene order along chromosomes, and its chromosome structure and number

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problems with molecular identification of a species

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what degree of dissimilarity should be the cutoff?

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ecological identification of a species

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relates species to the similarity of lifestyles and habitats/conditions

used mostly for prokaryotes (bacteria)

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problems of ecological identification of a species

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many species will have similar ecology

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evolutionary identification of a species

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looking at evolutionary trees and see if they come from a common ancestor or not

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species concept

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way of defining the concept of a species or distinguishing species from anothe

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biological species concept

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defines a group of individuals whose members have the potential to interbreed with another to produce viable, fertile offspring

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evolutionary lineage concept

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species should be defined based on the separate evolution of lineages

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lineages

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a series of species that forms a line of descent

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ecological species concept

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each species has an ecologic niche

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general lineage concept

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each species is a population of an independently evolving lineage

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reproductive isolating mechanisms

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prevent interbreeding between different populations; pre and post -zygotic

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types of pre zygotic mechanisms

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habitat, temporal, behavioral, mechanical, and gametic isolation

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types of post zygotic mechanisms

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reduce hybrid viability, hybrid sterility, and hybrid breakdown

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habitat isolation

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species occupy different areas/habitats or have geographic barriers and therefore do not come in contact to mate

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temporal isolation

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the species reproduce at different times

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behavioral isolation

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courtship rituals and other behaviors are unique to species and act as a barrier

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mechanical isolation

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morphological differences in genitalia prevent successful intercourse

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gametic isolation

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fertilization unsuccessful due to gametic incompatibility

important to species that release gametes into water or air

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post zygotic barriers

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are less common and are more costly in terms of energy and resources used

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reduced hybrid viability

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fertilized gee doesn't develop past an early embryo

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hybrid sterility

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hybrid survives into birth, but is sterile

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hybrid breakdown

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hybrid viable and fertile, but subsequent generations develop genetic abnormalities

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speciation

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accumulation of genetic changes that ultimately promote enough differences so that a population constitutes a whole new species

requires interruption of gene flow between populations

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how speciation occurs

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1. due to abrupt events like changes in chromosome number

2. arise out of adaptation to ecological niche

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cladogenesis

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splitting or diverging or a population into two or more species

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allopatric speciation

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most prevalent way for cladogenesis to occur; involves the geographic isolation of populations

interrupts gene flow, eventually creating new species

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hybrid zone

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where two populations can meet and interbreed because geographic separation is incomplete

once gene flow is greatly diminished, the two population can have enough reproductive isolation to lead to speciation

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adaptive radiation

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single species evolves into an array of descendants

they may differ in habitat or behavior

can also be caused from drastic environmental change

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sympatric speciation

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no physical barriers to interbreeding, yet speciation occurs

can be from adaptation to sub-habitat

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causes of sympatric speciation

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adaptation to local environments, polyploidy, sexual selectin

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polyploidy

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causes immediate reproductive isolation; where an organism has more than two sets of chromosomes and now gametes are no longer compatible

plants more tolerant than animals

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allodiploid

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an organism that has one set of chromosomes from two different species

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allotetraploid

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an organism have two sets of chromosomes from both parents, for a total of four sets

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evolutionary developmental biology

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compares the development of different organisms to understand ancestral relationships and evolutionary mechanisms that bring about evolutionary change

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development

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series of changes in the state of a call, tissue, organ, or organism

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pattern formation

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a specific body pattern formed from four processes

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four processes of pattern formation

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involves the genes that influence cell division, cell migration, cell differentiation, and cell death

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apoptosis

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the death of a cell

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changes to a developmental gene can lead to a rapid change of...

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the morphology of an organism will determine where and how things develop in the embryo and into adulthood

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hox genes

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determine the development of body plans, the more hox genes, the more complicated the body plan

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order of complication of hox genes

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sponges -> anemones -> flatworms -> insects -> chordates -> mammals

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heterochrony

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evolutionary changes in the rate or timing of developmental events