Exam 3 - Deuterostomes, Animal Evolution, Reproduction Speciation

all animals in the chordate phylum share these characteristics that appear at some stage during their development:

• notochord

• dorsal hollow nerve cord

• pharyngeal gill slits

• post-anal tail

• endostyle/thyroid gland

class asteroidea

sea star

class ophiuroidea

brittle stars

echinoidea

sea urchins, sand dollars

crinoidea

sea lilies

holothuroidea

sea cucumbers

5 classes under the echinoderm phylum

• asteroidea

• ophiuroidea

• echinoidea

• crinoidea

• holothuroidea

adult echinoderms have _________ symmetry

pentaradial

larval forms of echinoderms exhibit _______ symmetry

bilateral

echinoderms

• capable of regeneration

• water vascular system

• lack a head region, but do have a nerve ring

binary fission

occurs in prokaryotic microorganisms and in some invertebrate organisms; after a period of growth, an organism splits into two separate organisms

budding

results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals

fragmentation

the breaking of the body into two parts with subsequent regeneration.

budding occurs commonly in invertebrate animals such as:

corals and hydras

parthenogensis

an egg that develops into a complete individual without being fertilized. the resulting offspring be either haploid or diploid, depending on the process and the species

deuterostomes

anus forms first

chordates have _____ symmetry

bilateral

unochordata

turnicates

tunic

cellulose-like carbohydrate material that covers the whole body

adult turnicates are:

• sessile

• do not possess a notochord, dorsal hollow nerve cord, or post-anal tail

the “tadpole” larval form of turnicates:

possess all structures of a chordate

turnicate larva/ “tadpole”

turnicate development

some tunicate species may reproduce by:

budding

gnathostomes

“jawed mouth”, fish and tetrapods

tetrapod

“four-footed” amphibians, reptiles, birds, mammals

agnathan

jawless

haikouella

haikouella

chordate, has some advanced cephalization, craniate-like

hagfish

chordate with a head but no jaw

sexual reproduction

allows genetic variation

asexual reproduction

genetically identical to the parent

external fertilization

• can result in a greater mixture of genes within a group

• offspring produced must mature rapidly

• survival rate of eggs is low

internal fertilization

• protects the fertilized egg from predation or dehydration

• fewer offspring

• higher survival rate

zygote to blastula

gastrulation

blastula folds upon itself to form the three layers of cells

endoderm

internal layer; lung, thyroid, and digestive cells

mesoderm

middle layer; muscle cells, red blood cells, and tubule cells of the kidney

endoderm

external layer; skin cells of epidermis, neurons

organogenesis

organs form from the germ layers through the process of differentiation

differentiation

when the embryonic stem cells express specific sets of genes which will determine their ultimate cell type

formation of the neural tube

why is exposure to toxins especially dangerous during the first trimester?

all of the organ systems are in their initial development stages

adaptation

a heritable trait that helps an organisms survival and reproduction

divergent evolution

2 species that evolve in diverse directions from a common point

gene pool

shared pool of DNA information among organisms able to produce viable offspring together

reproductive isolation

driver for divergent evolution or differences in lineages

types of reproductive isolation

prezygotic v.s postzygotic barriers

prezygotic barrier

before mating/fertilization

postzygotic barrier

after fertilization

how can a postzygotic barrier occur?

• embryo doesn’t survive

• if embryo survives, adult may be sterile (ex: mule)

prezygotic barrier types

• habitat

• temperate

• behavioral

• mechanical

behavioral isolation

when the presence or absence of a specific behavior prevents reproduction

species

group of individual organisms that interbreed and produce fertile, viable offspring

why are tunicates classified as chordates?

at some point in their lives, they have a dorsal hollow nerve cord, notochord, pharyngeal slits, and a post-anal tail

what adaptations permitted the transition from water to land?

limbs and digits and having lungs

stages of development:

fertilization > cleavage > gastrulation > neurulation > organogenesis > growth

which germ layer will form the skin cells of the epidermis and the neurons of the brain?

ectoderm

which germ layer will form the dermis of the skin and muscle?

mesoderm

broadcast spawning

mechanism for fertilization and colonization of new environments for sessile aquatic organisms (ex: sponges)