topic 13: evolution of animals II Flashcards
Define key characteristics of invertebrates
- absence of backbone (spine)
- 95% of species
- ancestral traits lost
define metazoa based on anatomical characteristics + put into clades
- sponge
- 770 MYA
diploblastic
radial symmetry
sessile
no true tissues
define eumetazoa based on anatomical characteristics + put into clades
- 680 million years ago
- diploblastic + radial symmetry (2 embryonic tissues)
Ctenophora:
now include layers of tissue
- sensory epidermis
- nervous system
Cnidaria: (jellyfish)
- sessile poly + swimming medusa
- hydrostatic skeleton (pressure in cavity to help move, by contracting outer layer)
Place the evolution of body symmetry and the embryological formation of the mouth on a phylogeny
- bilateral symmetry and tripoblasty (mesoderm) evolved at same time
- 670 MYA
define lophotrochozoa based on anatomical characteristics + put into clades
protostome animals:
possess either:
- lophophore: crown of ciliated tentacles around the mouth (feeding)
-trochophore: specific larval stage
- examples: Mollusca (snails)
define ecdysozoa based on anatomical characteristics + put into clades
- largest group
- protostome animals
- produce exoskeleton (cuticle + molt this (ecdysis)
-this allows animals to grow - exoskeleton rigid and made of chitin + protein
-segmentation of functional units - presence of ganglions (nerve cell body cluster)
- examples: insects, beetles, spiders
define deuterostomia based on anatomical characteristics + put into clades
- bilateral symmetry
- deuterostome (anus first)
1) echinodermata (starfish)
- water circulatory system (ambulatory)
- nutrition, respiration, movement, excretion
define chordata based on anatomical characteristics + put into clades
Justify the importance of the notochord in the evolution of vertebrates
- 530 MYA
- monophyletic group
- notochord:
- skeletal element for developing embryo
- front to back of animal
- rigid + flexible structure for muscles to attach to, important for locomotion
- derives from mesoderm
- dorsal nerve chord (ectoderm):
- sensory info to CNS
- pharyngeal slits behind mouth: (filtration, gas exchange)
- post anal tail, skeleton, muscles
Explain paedomorphosis in urochordates (tunikates)
- vertebrates may have evolved through paedomorphosis
- preserves some characteristics of the larval stage (retention of juvenile features of ancestor)
- larvae evolved ability to reproduce before metamorphosis
- loss of 4 hox genes
vertebrates
skeletal system formed by by spinal cord
- protects dorsal nevre tube
- muscle attachment
- solidification of vertebrae (cartilage, bone)
- duplication of hox genes
Associate key innovations of vertebrates with the names of the clades they define (8)
1) notochord
- urochordata
2) vertebrae (cyclostomes)
- no jaw
- myxini (hagfish), petromyzontida (lamprey)
3) jaws, mineralized skeletons (gnathostomes)
- condrichytes (sharks): cartilage skeleton, placoid scales, homologous to vertebrate teeth (similarly due to shared ancestry)
- Intel fertilization with 3 modes of reproduction
- oviparous: egg laying + hatching outside
- ovoviviparous: egg hatches in uterus, embryo feeds on egg yolk
- viviparous: embryo feeds from mother through placenta
- osteichthyes (bony fish)
- calcium phosphate bones
- dorsal swim bladder
4) lungs/derivatives (osteichythyans)
- ray finned (no internal skeleton)
5) lobed fins
- lobed fin fish
- walk on land
- internal skeleton to which muscles attach
- lung fish: functional lungs homologous to tetrapod lungs
- possess gills
6) limbs with digits
- tetrapods
- new niches
- 4 limbs with digits
- amphibians
7) amniotic egg
- reptiles (adaptations: ectothermic -> control body temp, scales - desiccation)
- birds: reptiles + dinosaurs
- 4 membranes layers in eggs
- chorion: outer membrane (gas exchange)
- amnion: surrounds cavity (mechanic protection)
- allantois: surrounds disposal sac (metabolic wastes)
- yolk sac: stock of nutrients
8) milk
- mammals
- mammary glands + produce milk: source of proteins, carbs, lipids, minerals, vitamins
Organize the key innovations of tetrapods on a phylogeny
- four limbs with digits
Explain how specific structures found in the early tetrapods allowed vertebrates to colonize land
- new land niches, adaptive radiations
- new ranges in temp, humidity, protection against predators, less competition
adaptations leading to colonization of land
- body support against gravity (not needed in water)
- breathing in air
- hearing in air
- resistance to dryness
- vascular system with lungs + organs (blood throughout body against gravity)
Classify adaptations based on the physical or chemical challenges faced by tetrapods on land (in mammals)
- endotherm: internal way to maintain body temp, helps enzyme functions
- larger brain with ability to term
- differentiated teeth with specific functions
- hair and fat layer under skin (insulation)
- kidneys (excretion of metabolic waste + water retention) against dryness
primates:
- Opposable thumb (adaptation for grasping)
- Large brain and short jaw
- Parental care and social behaviors
- Tree-dwelling animals (hand-eye coordination)
- Overlapping visual fields (orbits located at the front of the skull)
binocular vision (depth perception)
Define and identify exaptations
- adaptation used for new function but not initially selected for
- feathers: first used for temp regulation, courtship, protection, camouflage
- later used for flight
