Untitled Quiz

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Animals are eukaryotic, multicellular, heterotrophic organisms that obtain nutrients by ingestion and digest their food within their bodies.
They possess nervous and muscle tissue, and evolved from a colonial protist called a choanoflagellate.
The Cambrian explosion (545 mya) marked the rapid diversification of animal life, with the fossil record revealing the evolution of all phyla present today.

The big 9 phyla (Arthropoda, Nematoda, Platyhelminthes, Annelida, Mollusca, Chordata, Echinodermata, Cnidaria, and Porifera) are more diverse and complex.

The Cambrian explosion was a period of rapid diversification, with multiple factors contributing to the ignition of this event.
Proposed hypotheses include:
- New predator-prey relationships generating diversity through natural selection (H1).
- An increase in oxygen levels enabling animals to develop higher metabolic rates and larger body sizes (H2).
- The evolution of Hox genes enabling developmental flexibility (H3).

Hox genes are transcription factors that regulate gene expression during development.
They are ordered in the same way as they are expressed in the body, controlling the development of body parts along the body plan.
Mutations in Hox genes can lead to innovation and variation in body plans.
Duplication of Hox genes or whole Hox clusters can lead to the creation of new body parts.

The evolution of vertebrates from invertebrates is characterized by the development of a vertebral column and internal skeletons.
Vertebrates belong to the phylum Chordata, which also includes invertebrates such as cephalochordates and urochordates.
Chordates share five key traits: notochord, dorsal hollow nerve cord, pharyngeal gill slits, postanal tail, and an endostyle or thyroid gland.

The Cichlidae family of fish exhibits a phenomenon of rapid speciation and reproductive isolation in lakes of East Africa.
Over 3000 known species of cichlid fish exist worldwide, with over 500 endemic species in Lake Victoria and Lake Malawi.
Interbreeding between endemic cichlid fish forms in Lake Victoria still produces viable and fertile hybrids.
Laboratory experiments have shown that reproductive isolation relies on prezygotic (sexual behavior) barriers between morphologically similar species.

Sensory drive refers to the idea that an animal's sensory system and ability to perceive signals from others can be a selection pressure in mate choice.
Speciation through sensory drive may occur in cichlid fish, where variations in the long wavelength sensitive (LWS) opsin sequence are associated with speciation events.
The environment plays a crucial role in shaping perception and preferences, with the most effective visual signals being those that match local light conditions.

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