Animal Diversity Flashcards
What is an animal?
the unique aspect of animals is the way the cell is put together and how it interacts with other cells
Derived Traits:
1. Multicellular Ingestion heterotrophs
- Unique Tissues
- Lack cell walls
- Intercullular junctions
What is an animal?
multicellular Ingesting heterotrophs
multicellular Ingesting heterotrophs (compared to plants and fungi)
What is an animal?
unique tissues
e.g. muscle and nervous <- unique to animals BUT not all animals have muscles and nervous tissues
What is an animal?
Lack cell walls
Support provided by extracellular matrix (collagen(unique to animals) & proteoglycans) and cytoskeleton (microtubules and microfilaments)
What is an animal?
Intercellular junctions(
made of proteins
Tight junctions – (suture junctions) protein binding of neighboring plasma
membranes; water tight
Desmosomes – (anchoring junctions) – strong rivet like proteins that connect
tissues into strong sheets (e.g. muscles)
Gap junctions (communicating junctions) - provides a pore through which cellular products can be exchanged (important in heart beating) - heart communicates via gap junctions
Animals are _____.
Monophyletic
Evolutionary History of animals
- Choanoflagellates
- Late Proterozoic Eon(700MYA)
- Cambrian period(550MYA)
Evolutionary History of animals:
Choanoflagellates
closest protist relative of animals
Evidence
- Near identical morphology with sponge collar cells - Collar cells found only in animals and choanoflagellates (no other protist) - DNA sequence similarity
Evolutionary History of animals:
Late Proterozoic Eon
First animals 700MYA
- Ediacaran period – Ediacaran biota - first good animal fossils ca. 575 MYA
- Basic body plans developed (e.g. radial and bilateral symmetry; segmentation)
- segmentation is a crucial evolutionary step that allows animals to dominate
- segmentation = repeating units
- redundancy allows specific units to be mutated without destroying the organism. Allows significant diversification
Evolutionary History of animals:
Cambrian period
550 MYA
- Rapid increase in animal orders
- Major phyla established (see figure 32.11)
- Diversification likely caused by:
a. increase O2 – aerobic metabolism provides more ATP per unit of glucose
b. Diversifying selection – novel niche exploitation and predator prey dynamics
c. Hox gene duplications
- duplication = redundancy = evolution can toy with it - Animal diversity
- 75% of animals are insects
- 35% of all animals are beetles
- 5 % of animals are vertebrates
- < 0.001% are mammals(5000 or so total species but such a small amount of total animals)
Reproduction and Development
- Life Cycle
- Zygote Development
- Hox Genes
Reproduction and Development:
Life cycle
no alternation of generations
- Sexual reproduction (mostly)
- Flagellated sperm; large non-motile egg
- Diploid stage dominates the life cycle
- Fungi are the exact opposite of us
Reproduction and Development:
Zygote Development
- Zygote undergoes cleavage(cell divisions) –> Blastula (hollow ball)(blastocoel= hollow)
- Bastula undergoes gastrulation –> gastrula
- Gastrula has defined endoderm and ectoderm
Reproduction and Development:
Hox genes
master regulatory genes that dictateDEVELOPING body plan.
- Evolutionarily conserved – means strong selection against modification, causing
these gene to be similar across different animals. - Linear correlation btw body axis and chromosomal position (odd!)
- no explanation known
- Small mutations lead to big changes (e.g. antennapedia in fruit flies)
- legs where antenna should be
- Gene duplications allow greater anatomical complexity
Animal Body Plans:
Symmetry
Bilateral versus Radial
- Radial = cutting a circular pie = always symmetric
- Bilateral = 1 axis to cut on for symmetry
