Ib 104 Unit 2

what does true breeding mean?

when plants are self-pollinated, this causes offspring to be the same variety as the parent.

what is the genetic basis of a true breeding parent?

two alleles that are the same

what is the genetic basis of the F1 generation hybrids?

two different alleles

what is a phenotype?

an observable trait

what is a genotype?

genes responsible for traits

Prezygotic Barriers

habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation- no successful mating or fertilization

postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown- individuals or their offspring are not fertile

allopatric speciation

populations are geographically isolated, gene flow is interrupted from habitat change or colonization.

sympatric speciation

speciation occurs in populations that live in the same geographic area

a species

a group of populations whose members have the potential to interbreed in nature, produce viable fertile offspring, and do not produce viable offspring with members of other such groups

Phylogeny

the evolutionary history of a species or group of related species

systematics

a discipline focused on classifying organisms and determining their evolutionary relationships

taxonomic groups in order from broad to narrow

domain, kingdom, phylum, class, order, family, genus, and species

Branch point

point that represents the divergence of two evolutionary lineages from a common ancestor

evolutionary lineage

a sequence of ancestral organisms leading to a particular descendant taxon

sister taxa

groups that share a common ancestor that is not shared by any other group

shared ancestral character

character that originated in an ancestor of the taxon

shared derived character

evolutionary novelty unique to a particular clade but may still have a shared ancestral character

Radial Symmetry

animals are sessile or planktonic, body parts arranged around a single central axis, drift or swim weakly

Bilateral Symmetry

body parts are arranges around two axes of orientation, the head-tail and the dorsal- ventral. 

what are the three layers of tissues from outside in?

ectoderm, mesoderm, endoderm

coelom

body cavity surrounded by tissues derived from mesoderm

protosome

blastopore develops into mouth

deuterostome

blastopore develops into anus

sponges

do not belong to eumetoazoa, they do not have tissues

porifera

asymmetrical, no body cavity (pores), no segmentation, spicules for support- ex: sea sponge

cnidaria

radial, 1 mouth, no segmentation, stinging cells- ex: jellyfish, coral, sea anemone

platyhelmintha

bilateral, 1 mouth, flattened body shape to increase SA volume- ex: tapeworms and planaria

annelida

bilateral, 1 mouth 1 anus, ringed segments with specialization of segments- ex: earthworms and leeches

mollusca

bilateral, 1 mouth 1 anus, body composed of visceral mass, muscular foot and a mantle, sometimes a shell- ex: snails, clams, octopi, clams

arthropoda

bilateral, 1 mouth 1 aunus, jointed body appendages, chitin exoskeleton- ex: insects, crustaceans, spiders, scorpions

chordata

bilateral, 1 mouth 1 anus, notochord and hollow dorsal nerve tube- ex: mammals, birds, reptiles, amphibians, and fish,

medusozoans

cnidarians that produce a medusa (jellies)

anthozoans

occur only as polyps, include sea anemones and corals