exam 2 evolution

biological evolution

biological evolution

is the major factor affecting living things both historically (past) and in ecological realms (present and recent)

speciation

produced biodiversity (species richness) as we observe today

Extant Populations

Surviving (living) populations that contain information about their evolutionary history and adapt to their present environments.

extinct

no longer in existence and is a fate awaiting all organisms including humans.

biosphere

the part of Earth where life exists which includes water, oxygen, etc... and 99% of all creatures that have ever lived are extinct

microevolution

something new has arisen within a population's gene pool and happens by natural selection or chance. it allows species to adapt to their environment.

genetic drift

random changes in organisms generated by chance events

Macroevolution

the evolution of new characters or character states within a population that may markedly identify a new species when genetically separated from its ancestor

grade

a new condition in the morphology and/or physiology of a lineage.

Speciation is the devolopment of...

the development of a new species (population lineage) after it becomes genetically separated from its ancestral population. its not due to micro or macro evolution but by the separation of new evolutionary lineages.

whats a species evolutionarily speaking?

the development of a new species (population lineage) after it becomes genetically separated from its ancestral population

asexual species

no sexes, no gametes and no fertilization. It produces asexually which makes an identical clone of itself. Most common organism that does this is protists and bacteria.

Unisexual Species

reproduction normally includes 1 sex (female), one gamete develops (egg); no fertilization (parthenogenesis, including gynogenesis); and asexual reproduction (clones)

Parthanogenesis

development of an egg without gamete fusion (fertilization)

bisexual species

two sexes; male and female have gametes and they take place in fertilization and sexual reproduction (ex: animal reproduction)

Evolution (darwins theory)

The world is not constant or recently created, but is gradually changing and organisms are transformed through time.

Common Descent (darwins theory)

Every group of organisms descended from a common ancestor and all life has descended from the original life form.

Multiplication of Species

Species multiply, either by changing through time into a daughter species or by geographical isolation of a founding population that evolves into a new species.

Gradualism

Evolutionary change takes place gradually (gradualism) and not by sudden production of species (saltation) that represents a new type.

Natural Selection

Evolutionary change comes about because of the selection for individuals that survive in nature because of their better-adapted combination of heritable characters, which are then passed on to the next generation.

macroevolution

observable evidence does support macroevolution as the origin of a new species, and does it lead to new characters appearing within an evolutionary lineage

gene flow

exchange of genes between populations by non random mating

intergradation

population of its own species

hybridization

population with one or more species

fitness

better adapted individuals as having higher genetic values and leads to populations getting the trait overtime

differential reproductive success

buildup in populations of individuals expressing the advantageous phenotype

gradualism

evolutionary changes are a slow process and is primarily done through natural selection

equilibrium selection = ?

stabilizing selection

stabilizing selection

is not microevolution, but for equilibrium frequencies thus theres no gene frequency changes occuring

directional selection

form of natural selection that allows populations to adapt to changing environments by allowing a previously lesser-adapted variant to over influence the frequency of individual reproductive success.

disruptive selection

Natural selection for more than one phenotype in a population

polymorphisms

DNA variants that occur within a specific population at a frequency greater than 1%

heterogeneous environment

the presence of unrelated or differing parts within an environment.

morphotypes

group of species with similar morphology (like bones) and is involved with disruptive selection.

Assortive mating

sexual selection based on favoritism of a male or due to traits that are favorable to them (height, physical structure, etc...)

Genetic drift

change in genotypic frequencies by chance alone

bottleneck effect

a type of drift whereby a few survivors of a natural catastrophe have less genetic variation than did members of the ancestral population before the cataclysmic event.

founder effect

common type of genetic drift where a small founding population colonizing a new area becomes genetically separated from its ancestral gene pool, but contains less genetic variation than was found within its ancestor's gene pool.

Intergradation

gene flow from other populations of the same species with different gene frequencies/phenotypes that adds new genetic combinations to a population.

Interspecific hybridization

gene flow from populations of different species, and can lead to new genetic combination at the microevolutionary level or even the macroevolutionary level depending on the genes being transferred.

Mutation pressure

a random way of altering gene pool frequencies in a population by either changing the frequencies of the genes (alleles) already present or by producing new gene variations that increase the overall genetic variation within the population

Macroevolution is the development of

new genetic characters or character states within a species or a subpopulation of that species. It may or may not be associated with formation of a new species.

punctuated equilibrium

where new forms develop rapidly and then remain virtually unchanged until going extinct.

divergent evolution

the group, such as a taxonomic Class, tends to split rapidly into separate lineage segments

adaptive zones.

regarded as different environmental zones opened up into which different groups evolve new characters allowing them to successfully exploit those zones

adaptive radiation

after the extinction of many species (like the Mesozoic era when the dinosaurs died) mammals entered the habitats left available, leaving the biosphere with many of the different mammalian Orders observed today

Sister species

normally occupy different geographic areas (allopatric),

sympatric

sister species reconnecting or currently connecting together (opposite of allopatric)

speciation event

what separates gene pools

cladogenesis

species branching [splitting] off their ancestor

anagenesis

a single lineage (population) evolves into another species through time (originally called vertical evolution)

allopatric speciation

Speciation that involves geographic separation of the new population from its ancestor

vicariance

when a population is passively separated by geological or environmental barriers being formed

dispersal

the active movement of a founding population over a barrier that is already present

sympatric speciation is the

genetic separation of a new species within the geographic range of its ancestor.

hybrid species

empirical evidence is related to the formation of a new species resulting from hybridization between two closely related species

Parthenogenic lizards

(unisexual species) are examples of species developing from hybrid origins

Parapatric speciation

related to speciation of adjacent populations that once were part of the total population.

zonal distribution

a species in different parts of a given area. Like living on different parts on a mountain which could be the result of parapatric speciation

diffusion

outward disposal

environmental exclusion

interspecific competition or by inability of each population to adapt to different environmental regimes

subspecies are:

an aggregate of local populations of a species inhabiting a geographic subdivision of the range of the species and differing taxonomically from other populations of the species

stage of speciation

an organism hat has not undergone sufficient divergence to be considered a full species.

individual variation

empirical observations that most species differ geographically. its also the uniqueness and variety among people's traits and behavioral tendencies.

geographic variation

have more than one historical cause, and some of those patterns fail to successfully relegate populations into distinct and definable taxonomic units

incipient species

newly formed species

geographic cline.

Geographic variation in individual variation within populations of the same species connected by gene flow can change from place to place in a gradual or in an abrupt manner

Intergradation

term used to describe gene exchange between members of phenotypically different populations of the same species along a cline.

ecotone

observed in an area containing intermediate environmental structure or characterized by having biotic communities composed of elements found outside the ecotone in both directions

Primary intergradation

between phenotypically different populations that have never been geographically separated, but because the intergrade zone is not abrupt, there is no way to draw a boundary to taxonomically define either population as a separate taxon (subspecies)

Secondary intergradation

between two phenotypically different populations that evolved in allopatry but have reconnected due to the failure of a geographic barrier.

gradual cline

Gradual change in geographic variation

melanin

provides pigmentation to the skin, eyes and hair and human ancestors are believed to have had lot of it. The closer you live to the equator, on the north or south side, the more you will have

Bergmann's Rule

species of vertebrates vary in size in the same way, with smaller body sizes being found in the tropics and larger sizes being found in temperate and arctic (antarctic) latitudes

Step clines

abrupt changes in geographic variation caused by sudden environmental changes in space with a narrow zone of primary intergradation, or due to secondary intergradation.

Species are:

separate lineages that are genetically detached from other lineages (like dogs and wolfs)

morphological species concept

morphological similarity is the prime characteristic for defining a species

typological species concept

defined a species by the morphological similarity of its members

type specimen

designated by the person describing a species, and was thought to be the "typical individual" that all other individuals could be compared to.

polymorphic

presence of two or more variant forms of a specific DNA sequence that can occur among different individuals or populations. tend to complicate any species concept based on morphological similarity.

plesiomorphic

trait(s) that are present in the ancestral and descendant species. Its determined that reproductive ability within lineage segments of closely related species was a plesiomorphic condition

viable offspring

embryo or fetus capable of living and reproducing outside the mothers womb. It was determined that reproductive ability within lineage segments of closely related species was a plesiomorphic condition

Premating mechanisms

prohibit the mating act (copulation in animals) to occur, so gametes are not wasted.

Postmating mechanisms

prohibit the production of successful hybrids, even though mating actually takes place (gametes are wasted).

postmakting mechanisms may be:

prezygotic, where the sperm of the male never fertilizes the egg, or B) postzygotic where fertilization does occur, but hybrids never reach a point of reproductive viability.

prezygotic

where the sperm of the male never fertilizes the egg,

postzygotic

where fertilization does occur, but hybrids never reach a point of reproductive viability.

gamete mortality

where sperm are killed by female immune system or by a non-equitable environment (e.g., ph differences).

embryonic mortality

embryo dies at some stage development

hybrid sterility

produces a mule

hybrid inviability

hybrid is unsuccessful at mating due to odd looks, smell differences, or behavioral differences; it is not recognized as being a member of the species.

contact zone

two species exist

emperical evidence shows 4 possibilities exist :

Empirical evidence shows that at least four possibilities exist: 1). The two populations come into contact and no mating takes place (premating mechanisms) - both species are found in the contact zone (two species exist). 2). The two populations come into contact and occasional mating takes place (postmating mechanisms) - both species and occasionally hybrids are found in the contact zone), but hybrids are normally selected against, so they are less common in the contact zone (two species exist. 3). The two populations come into contact and there is complete genetic introgression (full gene flow) takes place. 4. if individuals of the two populations hybridize and those hybrids form a new species

intergrades

all individuals contain a blend of character states from each population

Biological Species Concept

referred to as "the Isolation Concept", because the main focus is that species are reproductively isolated from other species.

species

a group of actually or potentially interbreeding individuals that are reproductively isolated from other groups

Species Recognition Concept (SRC)

does not associate speciation with the development of isolating mechanisms by natural selection between two lineages because that would require sympatric speciation (natural selection separating two groups in the same area). This concept identifies species as "the most inclusive population of individual biparental organisms that share a common fertilization system.

specific mate recognition system

develops in geographic isolation after sister groups split and occupy different habitats

Evolutionary Species Concept (ESC):

a single lineage of ancestor-descendant

populations, which maintains its identity from other lineages and has its own evolutionary tendencies and historical fate

Phylogenetic Species Concept (PSC)

irreducible grouping of organisms diagnosably distinct from other such groupings and within which there is a pattern of ancestry and descent.