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

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

echinodermata

radial, 1 mouth. start bilateral and then become radial- ex: starfish, sea urchins, and sea cucmbers

what are the five clades of echinoderms

asteroidea (sea stars), ophiuroidea (brittle stars), echinoidea (sea urchins and sand dollars), crinoidea (sea lillies) holothuroidea (sea cucumbers)

what are examples of jawless vertebrates

hagfish and lampreys

chondrichthyans

have a skeleton composed primarily of cartilage (shark, ray, chimera/ratfish)

osteichthyes

bony fish, largest class of vertebrates, instead of cartilage they have bones, and have a swim bladder for buoyancy.

what is the function of the dorsal fin?

stabilizers so fish don’t roll

oviparous

eggs hatch outside the mothers body

ovoviviparous

eggs are retained within the oviduct, young are born after hatching in the uterus.

viviparous

young develop in the uterus and are nourished by a yolk sac placenta, absorption of fluid or by eating other eggs.

ray-finned fishes

over 27,000 species, modifications in body form and fin structure affect maneuvering, defense, and other.

lobe fin lineages

coelacanths, lungfishes, tetrapods

what is unusual about the lungfish’s circulatory system?

they live in environments with low oxygen levels so they utilize gills to diffuse oxygen and lungs to gulp water and take in oxygen

amphibians three clades

salamanders (Urodela, tailed ones), frogs (Anura, tail-less ones), caecilians Apoda, legless ones)

Salamanders (urodela)

550 species, some are aquatic but most live on land as adults, paedomorphosis

frogs ( Aunura)

5,420 species, lack tails and have powerful hind legs, frogs with leathery skin are toads.

caecilians (apoda)

170 species, legless and nearly blind, resemble earthworms, legs lost as a secondary adaptation

what does the term amphibian mean

both ways of life- many species live first in water and then on land.

amniotic egg

egg that contains four membranes that protect the embryo, key adaptation for life on land, reduced dependence on water for reproduction

reptiles characteristics

scales containing keratin to protect, shelled eggs on land, fertilization occurs internally, ectothermic- absorbing external heat

Diapsids

earliest reptiles that resembled lizards about 310 million years ago, pair of holes on either side of skull where muscles attach to jaw

diapsids three main lineages

turtles, lepidosaurs ( tuataras, lizards, snakes), archosaurs (crocodilians)

tuatara

Lepidosaur- lizard like species, live in 30 islands off the coast of New Zealand, threatened by rats.

turtles

351 known species, most closely related to crocodilians and birds, lost the holes in the skull.

Lizards and Snakes

lepidosaur- squamates. around 10,425 species.

snakes

move by producing waves of lateral bending from head to toe, can use belly scales to grip the ground

crocodilians

24 species, restricted to warm regions of the globe, descendants of quadrupeds.

characteristics of birds

no urinary bladder, one ovary, small gonads, toothless mouths, air-filled bones with honeycombed internal structure

ratites

order of flightless birds ostrich, rhea, kiwi, cassowary, and emu

what was the earliest known bird?

archaeopteryx

mammal characteristics

mammary glands, hair and a fat layer, kidneys, endothermy a high metabolic rate, respiratory and circulatory systems, extensive parental care, teeth modified for shearing, crushing, or grinding.

when were the first true mammals alive?

during the jurassic period?

three major lineages of mammals

monotremes, marsupials, eutherians

monotremes

egg laying mammals, found in Australia and New Guinea, females lack nipples and secrete milk from glands, echidna and platypus

marsupials

higher metabolic rates, nipples, birth of live young, placenta, , live in australia snd the americas, kangaroos, wolverine, woodchucl

eutherians

placental mammals, complete emdyonic development within a uterus, elephants, dolphins

primates

hands and feet, digits, fingers and fingerprints, forward looking eyes, parental care, lemurs, tarsiers, monkeys and apes

three main groups of living primates

lemurs, tarsiers, anthropoids

four genera of great apes

pongo, gorrilla, pan, homo

earliest trace of humans

homo sapiens fossils found from ethiopia that are 195,000 and 160,000 years old

Heterozygous gene

Xx

Natural Selection

genetic variation due to differences in alleles, to help an animal survive (color or neck length) allows them to survive and reproduce.

genetic drift

two main types: bottleneck effect and founder effect. changes allele frequencies and reduces genetic diversity. not adaptive

bottleneck effect

drastic reduction in population size due to a sudden change in environment or random event

founder effect

colonization’s of a new habitat by a few individuals

gene flow

movement of alleles among populations through the movement of fertile individuals or gametes, reduces genetic differences between populations over time

directional selection

favors individuals at one extreme end- giraffes

stabilizing selection

favors intermediate variants- different colored mice

disruptive selection

favors induviduals at both extremes- both light and dark colored moths

how can we define a biological species?

a group of populations whos members have the potential to reproduce viable, fertile offspring and do not produce viable offspring with members of other such groups

pre-zygotic barrier

mechanical isolation - physical incompatibility ie- snails that have shells coiled in opposite directions, physically prevents their genitalia from aligning properly

postzygotic barrier

reduced hybrid fertility- hybrid offspring are infertile, like a mule, and offspring cannot reproduce

taxonomic groups in order

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