BIOTEST4

Five major animal lineages

Five major animal lineages

sponges, comb jellies, corals and jellyfish, protostomes, deuterostomes

protostomes are

• diverse and abundant (most of all animal lineages)

ecological roles

• live in virtually all aquatic and terrestrial habitats

• can be herbivores, carnivores, detritivores -extends to human health

• food sources

model organisms

fruit fly and flatworm

protostomes share a

bilaterian ancestor that was bilaterally symmetric and triploblastic

developmental characteristics

1. embryonic development of mouth before anus

2. Inability of isolated early embryonic cells to develop into complete embryo

3. Formation of coelom by splitting of blocks of mesodermal cells

two major subgroups of protostomes

1. lophotrochozoa - includes mollusks and annelid worms

2. ecdysozoa - nematodes and arthropods

water to land transition

opens up entirely new habitats and new resources to exploit

adaptive radiation of plants

correlates with the protostomes transition to land

new adaptations of protostomes

1. Exchange gases

2. Avoid drying out

3. Hold up their bodies under their own weight

roundworms and earthworms

• high surface area to volume ratio -increased efficiency of gas exchange

terrestrial arthropods and mollusks

• have gills or other respiratory structures located in the body

• minimized water loss when moving onto land

animal belongs to lophotrochozoan if...

Has a (not all three needed)

• lophophore -suspension feeding

• trochophore - larvae swim and may feed

• spiral cleavage

rotifers

Cilia in the corona create a current that enables suspension feeding on microscopic food particles

platyhelminthes (flatworms)

Turbellarians (free-living), flukes (endoparasites), and monogeneans (ectoparasites) have a “blind” digestive tract with only one opening for ingestion of food and elimination of wastes; tapeworms (endoparasites) have no gut or mouth and absorb nutrients across their body wall

annelida

Polychaetes have diverse feeding strategies such as suspension feeding, mass feeding, and deposit feeding; almost all oligochaetes are deposit feeders in soils; about half of leeches are ectoparasites while others are predators or scavengers

Mollusca

Snails, chitons, and cephalopods have a rasping structure called a radula that is specialized for diverse feeding strategies; bivalves use gills for suspension feeding

ecdysozoan

grows via molting - shedding of exoskeleton or cuticle

nemotoda

Sexes are separate in most species (C. elegans is mostly hermaphroditic); internal fertilizatioin leads to egg laying and direct development of offspring; individuals molt four times during lifetime

tardigrada

Sexes are separate in most species; some are parthenogenic; some are hermaphroditic, able to self-fertilize; fertilization is usually external; may molt up to 12 times during growth

onychophora

Sexes are separate in almost all species, and females are usually larger than males; fertilization is usualy internal; most species are ovoviviparous

arthropoda

-Use specialized mouthparts to consume all types of foods from detritus and live prey to flower nectar and blood; serve diverse ecological roles

• Most use jointed appendages for walking, running, jumping, and swimming; most also have wings; insect larvae such as maggots, caterpillars, and grubs move using hydrostatic Skeletons

• Sexes are usually separate, and sexual reproduction is the norm (parthenogenesis is rare); fertilization is usually internal; may or may not have larvae and metamorphosis

what is an arthropod

most important phyla in ecdysozoa

arthropod body plan

1. Segmented body plan

2. exoskeleton

3. jointed appendages

origin of wings

did not come from limbs - changes in the cuticle

types of arthropods

1. myriapods

2. insects

3. crustaceans

4. chelicerates

myriapoda

relatively simple bodies with a head region and a long segmented trunk with many legs

insecta

remarkably diverse and abundant in terrestrial environments; body has three tagmata: head, thorax, abdomen

crustacea

most diverse arthropods of the sea; body has three tagmata or two (cephalothorax and abdomen)

chelicerata

diverse on land, body has two tagmata: cephalothorax and abdomen

deuterostomes

"second mouth" developmental distinction between protostomes and deuterostomes is now blurred

three phyla

1. echinodermata

2. hemichordata - acorn worms

3. chordata

echinoderm

"spiny skins" - named for spines and spikes observed in many species

deuterostomes have high diversity in

1. Adult body plans

2. feeding methods

3. locomotion

4. reproduction

echinoderm synapomorphies

1. redial symmetry in adults

2. endoskeleton

3. water vascular system and tube feet

chordate morphological features

1. openings in throat called gill slits

2. dorsal hollow nerve cord

3. notochord runs length of body

4. muscular post-anal tail

three main subphyla of chordates

1.cephalacordate 2. urochordates 3. vertebrates

cephalacordate

small torpedo shaped animals with "fishlike" appearance - mobile suspension feeders - live on ocean floor

urochordates

have external coat of polysaccaride - covers and supports body

vertebrates

dorsal hollow nerve cord elongated into spinal cord; pharyngeal slits in embryos

vertebrate synapomorphies

1. vertebrate - protects spinal cord

2. cranium - protects brain and sensory organs

cartilage

strong, flexible tissue (polysaccarides)

bone

dense tissue and blood vessels (calcium phosphate)

vertebrate brains

1. forebrain - sense of smell (forms cerebrum)

2. midbrain - associated with vision

3. hindbrain - balance and hearing *brain is key innovation in vertebrate evolution

jawed vertebrates contain

cerebrum and medulla oblongata

Data supporting evolution

1. new fossil evidence

2. phylogenetic analysis - combines fossil evidence and new data

3. evidence from developmental biology - can test relations between different vertebrate lineages

themes of evolution

1. most vertebrate are extinct

2. some traits evolved more than once

3. traits are sometimes lost

gnathostomes

jawed fish

rapid diversification of feeding strategies led to

dramatic adaptive radiation of fish

jaw formed by

mutations and natural selection

bony fish

1. Ray-finned fished

2. Coelacanths

3. Lung Fishes

Lobed-limbed fish

coelcanths and lungfish

lungs first appeared in

placoderms

origin of lungs hypothesis

predicts early fishes filled this space by gulping air from the surface

tetripods

animals with four legs; major event in evolution led to transition to living on land

3 major lineages of tetrapods

1. Amphibians

2. Mammals

3. Reptiles

Amniota

all tetrapods other than amphibians

amniotic egg

protective coating that reduced the rate of drying

three inner membranes

• embryo

• yolk

• waste

mammals

monophyletic group of animals named for mammary glands which produce milk; earliest seen ~195 mya; endotherms

three major lineages of mammals

1. egg-laying monotremes

2. pouch bearing

3. placenta

placenta

organ combining maternal and embryonic tissues

evolutionary advantages of placenta

1. offspring develop at constant, favorable temperature

2. offspring are protected

why is the yolk sac smaller in a placenta?

Because the need for nutrients is lower in a placenta because the embryo also obtains nutrients from their mother.

reptiles

monophyletic group; second major lineage of amniotes besides mammals; adaptations for life on land; skin is water tight; breathe through lungs and lay amniotic ends; ectotherms

Birds

part of the monophyletic group reptiles; also part of the monophyletic group dinosaurs; endothermic

Three lineages of wings and flight evolution

1. Pterosaurs

2. Birds

3. Bats

parental care

physiological, morphological, or behavioral investment that improvs the likelihood of offspring to survive; is believed to play major role in evolutionary success of birds and mammals

primates two min groupings

1. Prosimians ("before monkeys")

2. Anthropoids ("human-like")

primate characteristics

• hands and feet efficient for grasping

• flattened nails instead of claws

• relatively large brains

• color vision

• complex social behavior

• extensive parental care

• forward facing eyes

great apes

hominids; large bodies, long arms, short legs no tail; humans are the only bipedal hominid

Humans are closest related to

chimpanzees and bonobos followed by gorillas; common ancestor believed to exist 6-7 mya

Four typs of hominids

1. Gracile australopithecines

2. Robust australopithecines

3. Early Homo

4. Recent Homo

Gracile australopithecines

slender/bipedal

robust australopithecines

three species: Massive cheek teeth and jaws Very large cheekbones A sagittal crest—a flange of bone at the top of the skull

early homo

– Flatter and narrower faces – Smaller jaws and teeth – Larger braincases

recent homo

– Flatter faces – Smaller teeth – Larger braincases

derived character of humans is

bipedalism

fossil evidence supports what origins of humans?

Africa and subsequent migration

Have humans stopped evolving?

No all four processes of evolution still occur today