Homologoy and Analogy charecters of animals

Homologoy and Analogy charecters

1. Homology Homology refers to the similarity between structures, genes, or proteins that share a common ancestral origin. This means that homologous features have evolved from a shared ancestor and have since .

2. Homologous organs: Organs with similar structure and different function are called homologous organs.
For example, forelimbs of all vertebrates have the same internal structure, but they have different functions in different Organisms
Whales and dolphins - for swimming Bats- for flying
Primates- for holding
Cat - for walking
Even with these different functions, they all have the same internal structure. This indicates their common ancestry (divergent evolution).

3. Types of Homology Orthology : Genes or proteins with similar functions in different species. 2. Paralogy : Genes or proteins with similar functions within the same species. 3. Xenology : Genes or proteins with similar functions in different kingdoms.

4. Characters of Homologo A) Structural Homology* • Morphological similarity: Similar shape, size, and organization of body parts. • Anatomical correspondence: Similar arrangement of organs and tissues. • Embryological development: Similar developmental pathways. B) Molecular Homology* • DNA sequence similarity: Similarity in nucleotide sequences. • Protein sequence similarity: Similarity in amino acid sequences. • Gene orthology : Similar genes with similar functions.

5. C) Functional Homology* • Similar biochemical pathways. • Similar physiological processes. • Similar behavioral traits. D) Developmental Homology* • Similar embryonic development. • Similar pattern formation. • Similar cell differentiation. E) Phylogenetic Homology* • Shared ancestry. • Common evolutionary origin • Phylogenetic tree reconstruction.

6. Examples of homologous organs 1. Forelimbs of Vertebrates: The forelimbs of mammals, reptiles, birds, and amphibians share a common skeletal structure, adapted for diverse functions such as walking, flying, and swimming.

7. 2. Pentadactyl Limbs: The pentadactyl limb pattern, characterized by five digits, is found in various vertebrates, including humans, whales, bats, and horses.

8. Analogous organs Organs with different structure and similar function are called analogous organs. Have distinct ancestral backgrounds. Analogy is an evidence for convergent evolution where unrelated organism have similar features due to similar environment. They demonstrate the remarkable adaptability of life forms and the convergence of traits in response to shared ecological demands. Wings of insects and birds are examples.

9. Characters of Analogy Analogy characters refer to the similarities between structures, functions, or processes that have evolved independently in different organisms, often in response to similar environmental pressures. Here are some examples: A) Structural Analogy* 1. Wings in insects (e.g., butterflies, bees) and birds: Similar shape and function, but different composition and development. 2. Fins in fish and flippers in dolphins: Similar function, but different structure and development. 3. Eyes in humans and octopuses: Similar function, but different structure and development.

10. B) Functional Analogy* 1. Echolocation in bats and dolphins: Similar function, but different mechanisms. 2. Photosynthesis in plants and cyanobacteria: Similar function, but different pigments and pathways. 3. Thermoregulation in mammals (sweating) and birds (panting): Similar function, but different m echanisms . C) Behavior Analogy* 1. Migration patterns in birds and monarch butterflies: Similar behavior , but different cues and mechanisms. 2. Social organization in ants and humans: Similar social structures, but different communication and cooperation mechanisms. 3. Communication methods in dolphins and primates: Similar function, but different mechanisms.

11. Examples of Analogous Organs 1. Birds and Insects wings: Birds and insects have each evolved wings separately for flight, even though their wing structures and origins differ.

12. 2. Dolphins and Penguins Swimming: • In aquatic settings, dolphins and penguins have developed flippers independently to navigate and swim, despite their separate lineage.