Animal Diversity lecture 7

BIO1412

What makes an animal an animal?

Multicellular, heterotrophic, motile

What is the closest living relative to animals?

Choanoflagellates, 900 mya

Cambrian Explosion

A rapid burst of diversification leading to the establishment of many basic types of body forms seen today

Punctuated equilibrium

Evolution with long intervals of relative stasis with short periods of rapid diversification

What made the Cambrian so favorable for rapid diversification?

Increase in global O2, increase in ocean Ca2, increase habitats, evolution of hox genes

Hox genes

Family of genes that specify different regions of an animals body plan

What happened in the post Cambrian evolution?

Ordovician period, modern spinal column emerges, plants colonize land and then animals follow

What happened in the early Ordovician period?

First fishes, with evolution of armored plates

What happened in the late Ordovician period?

Bony jaws evolution, large predators

What are the two major lineages formed in the late Ordovician period?

Acanthodians the ancestors of sharks, and Placoderms the ancestors of bony fishes

What period followed the Ordovician period?

Devonian period, diversification of sharks and bony fishes, first lobe finned fishes evolved leading to the first vertebrate colonization of land

What happened at the end of the Triassic period?

Bony fishes diversified and an extinction event occurred

What happened after the Triassic period?

Jurassic period, brough increased body size and more habitats/niches

What happened after the Jurassic period?

Cretaceous period, the closest ancestors of modern fishes evolved and more large predators

What happened during the K-Pg boundary?

Diversification of many bony fishes

What did Lobe finned fishes do in the Devonian period?

Arose and diversified, and colonized land at the end of the period

What did lobe finned fishes led to the evolution of?

Tetrapods, amphibians, mammals, birds etc

Amphibians

Early species were fully aquatic later made transition to terrestrial lifestyle

Sarcopterygian is who’s ancestor?

Amphibians, it had lungs and appendages with support away from body

Who and when did birds crocodilians and reptiles early ancestor come from?

In the Pennsylvanian period, and Sauropsid lineage

Who and when did the mammals first ancestor arose?

Pennsylvanian period, Synapsids

Centralization

NS becomes central in body plan

Cephalization

Sensory structures are located in the head

What’s the first Extinction event?

Late Ordovician, 85% of all species due to volcanism and anoxia

What is the second Extinction Event?

Late Devonian, 70% of all species mainly reef organisms, ocean anoxia and global cooling

Whats the third Extinction event?

Permian Triassic, 81% marine and 70% terrestrial, global warming and ocean acidification

Whats the fourth extinction event?

Triassic-Jurassic, 70-75% of all species, volcanic eruptions, global warming and ocean anoxia