Question

29. What is Lamarckism, and what theory replaced it over the past few centuries? What two

    examples/mechanisms were given that demonstrate potential modern support for Lamarckism?

Answer 1

Lamarickism view was given by JB Lamarck who suggested that whatever the character aquired by organism in its life span are transferred to next generation and hence it's called theory or aquired charactor also he suggested that no. of species remains the same and one species after milion of years changes completely into another species.

This theory was later rejected by Charles Darwin theory of Natural selection who suggested that only those characters go to next generation which causes changes in germline not in somatic cells also species no. Keep on increasing and one species formed by Adaptation from existing species and ancestor species never lost so species diversity increases with time.

Among four main postulates or theory which lamarck sugested, all were disproved except one that was use and disuse organ are well accepted .

Example which he given to support his theory were:

A)Giraffe- ancester of giraffe were having small neck and fore limb and when surface vegatation become limited they start streching there neck to take leaves from higheted plant which we see today is organism with long streched neck and long fore limb.

B) aquatic birds like duck evolved from terestial ancester but thy moved to water due to less completion and more food and slowly they developed webs in between thier toes and wing become less developed.these character help these bird to swim in water and cannot fly.

Hope it's clear..thanks