Topic 20: Origin Of Animals Flashcards
What do ancestoral protists likely resemble?
This ancestral protist likely resembled modern
choanoflagellates, which are flagellated eukaryotes.
Choanoflagellates are _________ protists that are the closests relatives to animals
Opisthokont
Basal chaonoflagellates are ___, _____, and _____
Small, unicellular, and heterotrophic
How would you describe a chaonoflagellate?
They are collared flagellates with a funnel-shaped collar/microvilli at the base of the flagellum
What are microvilli?
re finger-like projections of the
cell membrane that captured bacteria.
What are animals hypothesized to evolve from?
Choanoflagellate-like ancestors
What are the three pieces of evidence that choanoflagellates closely resemble animals?
1) cell morphology
2) animals have a unique cell morphology
3) homolous DNA sequence
Did multicellularity evolve dependantly or independantly in many lineages?
Independantly
What are some evolutionary advantages to bein multicellular?
- the bigger you are, the harder is is to get eaten
- cell specialization
- more complexity and size
- long life span
- least predators on you
What era where multicellular animal fossils come from?
Ediacaran biota era
What are ediacaran biota?
Diverse, soft-bodied and non-motile marine organisms that have radial symmetry
Event that klet to a significat diversification of animal evolution
Cambrian explosion
What do the fossils from the cambrian explosion show
It showed a rapid evolution and increase of diversity of various bilaterian animals
(Most animals had a fossil from this era)
What are three hypothesis for the cambrian explosion
- evolution of predation: lead to more complex body structures
- oxygenation event: more oxygen suppotd greater body sizes and energtic lifestyles
- evolution of hox genes: facilitates in the diversification of complex body forms
Three eras of animal evolution
- paleozoic
- mesozoic
- cenozoic
What does the term invertebrates refer to?
An animal without a backbone
Are invertebrates monophyletic, para or polyphyletic?
Paraphyletic
What is the most critical era where mammals increased in size and diversity after the cretaceous mass extinction?
Cenozoic era
what are hypothesiss for the cambriage explosionÉ
evolution of predation, the great oxigenation event and the evolution of hox genes
