Summary Modification of basic body parts and Biogeography - Grade 11 Biology
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Course
Life Sciences
Institution
12th Grade
A detailed summary of the entire Modification of basic body parts and evolution Grade 11 Biology Topic as well as whole Biogeography Chapter. 2 in 1 summary.
Species connected to similar species nearby : ADAPTIVE RADIATION
● Members of a species moved to different environments.
● Those who moved had characteristics that allowed them to adapt to
these changing circumstances
● Were the ones that lived long enough to produce offspring
● The body plans became modified overtime and eventually new species
were filmed
MORPHOLOGICAL DIVERGENCE
➔ The development of different structural characteristics in organisms that
come from the same ancestor.
DIVERGENT EVOLUTION
➔ These formal homologies have certain features in common with each
other and with the ancestral stock from which they arose.
➔ Has enabled the Descendants to fill a wide variety of ecological niches
What are the characteristics of HOMOLOGIES (homology is similarity due to
shared ancestry between a pair of structures or genes)
➔ Homologous structures must be similar in :
1. Fundamental structure
2. position and developments
➔ However homologies :
1. Can be superficially different
2. may or may not perform the same function
VALUE OF HOMOLOGIES
● Suggest evolutionary linkages between groups that have diverged
from a common ancestor by adaptive radiation.
EXAMPLES OF HOMOLOGIES
● The forelimbs of the mammal has been modified for different kinds of
movement
● Mouthparts of insects have been modified to east different types of
foods
● Flowers have been modified to suit different pollinators
, PENTADACTYL LIMB
● Has five fingers or toes
● is found in all four classes of terrestrial vertebrates
● can be traced back to the fins of certain fossil fish
● the common ancestor was adapted by modification for different uses or
habitats for life on land
MAMMALIAN FORELIMB
● Mammals forelimbs share a similar arrangement of Bones
● They arise from the same embryonic, homologous structures.
● For example, bone structure of a whale fin and human forearm is
similar and therefore evidence that whales and humans are closely
related
● Through natural selection, the form of the forearm has been modified
over millions of years.
● This modification helps them to perform a variety of functions, and the
basic design remains the same.
● bones from shoulder to fingers, made up of five major segments and
five major joints.
● for mammals, primary function of forelimb is locomotion
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