The student is expected to: 7A analyze and evaluate how evidence of common ancestry among groups is provided by the fossil record, biogeography, and homologies, including anatomical, molecular, and developmental; 7D analyze and evaluate how the elements of natural selection, including inherited variation, the potential of a population to produce more offspring than can survive, and a finite supply of environmental resources, result in differential reproductive success;

Continued: 7E analyze and evaluate the relationship of natural selection to adaptation and to the development of diversity in and among species; 8B categorize organisms using a hierarchical classification system based on similarities and differences shared among groups; 8C compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals

KEY CONCEPT Amphibians evolved from lobe-finned fish.

Amphibians were the first animals with four limbs. Tetrapods are vertebrates that have four limbs. The fossilized remains of Tiktaalik roseae indicate it was a transitional species between fish and tetrapods.

Vertebrates that lack four limbs evolved from limbed ancestors. Amphibians are animals that can live both on land and in water.

A number of adaptations allow amphibians to live on land. large shoulder and hip bones mobile, muscular tongue middle ear breathe through skin or with gills or lungs

Amphibians return to the water to reproduce. Amphibians use many strategies to keep their eggs wet. lay eggs directly in water lay eggs on moist ground wrap eggs in leaves brood eggs in pockets on the female’s back

Tadpoles are aquatic larvae of frogs. During metamorphosis, tadpoles develop into their adult form. adult frog young frog tadpoles fertilized eggs Not all amphibians undergo metamorphosis.

Modern amphibians can be divided into three groups. Salamanders have a long body, four walking limbs, and a tail. There are over 300 species of salamanders.

Frogs are the largest amphibian group and include toads. There are over 3000 species of frogs. Glands in the skin of frogs and toads contain poisons that help to protect them from predators.

Caecilians are legless, burrowing, tropical amphibians. There are 160 species of caecilians.