Pattern of evolution

Contents
Patten of Evolution
 Evolution
 Convergent Evolution
 Analogous structures
 Divergent Evolution
 Homologous structures
 Parallel Evolution
 Coevolution
 Types of Evolution
• Macroevolution
• Microevolution
 Importance of pattern of evolution

Evolution
“Evolution, or change over time, is the process by which modern organisms have
descended from ancient organisms. ”
 Evolution also explains how modern organisms have descended from ancient
organisms.
 Evolution is the Process by which organisms pass on traits from generation to
generation.
 Explains the origin of new species and diversity.
Change over time

PATTERN OF EVOLUTION
Convergent Evolution
 In evolutionary biology, convergent evolution is
the process whereby organisms not closely related
, independently evolve similar traits as a result of
having to adapt to similar environments or
ecological niches.
 Animals come from different ancestral lineages
 Caused by environmental changes
 Also called convergence
Examples
i. shark and dolphin bodies,
ii. vertebrate and cephalopod eyes
iii. the relationship between bat and insect
wings,

Analogous Structures
 Convergent evolution creates analogous structures that have similar form or
function but were not present in the last common ancestor of those groups.
 Organisma have the same function but not same the structure.
 Analogous structures arise from convergent evolution.

Divergent Evolution
 “Divergent evolution is defined as what occurs
when two groups of the same
species evolve different traits within those groups in
order to accommodate for differing environmental
and social pressures”.
 Species gradually become different from its
ancestors
 Evolution resulted in multiple different species,
leading to speciation
 Homologous structure development
 Also called adaptive radiation
 Caused by environmental changes, migration

Examples of Divergent Evolution
• Darwin’s Finches
Finches on the Galapagos islands
evolved into many different species to eat
different foods.
• Polar bear and brown bear
• Red fox and kit fox

Homologous Structue
 In divergent evolution, homologous
structures are structures indicating a species is
diverging from its ancestor.
 These structures need not have the same function as
that of those of the species' ancestors.
 Same structure
 Different function
 homologous structures arise via Divergent evolution .
 Example
 the forelimbs of humans and bats
are homologous structures.

Parallel Evolution
 Some species evolve without converging on similar traits
or diverging to different traits. These species undergo
change, but they maintain a constant level of similarity to
each other. This process is known as parallel evolution.
 Parallel evolution occurs when two species evolve
independently of each other, maintaining the same level
of similarity.
 Parallel evolution usually occurs between unrelated
species that do not occupy the same or similar niches in a
given habitat

Examples
 Marsupials and placental mammals most
recently shared common ancestor 125-
150 million years ago.yet these similar
features appeared in each of the distant
relatives

Coevolution
 “The Process By Which Two Species Evolve In
Response To Changes In Each Other”
 Species that live in a close relationship with each
other, such as a predator-prey or symbiotic
relationship, often evolve adaptations to each
other in a process called coevolution.
Types of Coevolution
i. Parasite –host coevolution
ii. Mutualistic/Beneficial coevolution
iii. Predatory/prey coevolution

Examples of Coevolution
 Mutualistic/Beneficial coevolution
I. yucca moth (Tegeticula yuccasella)A female
yucca moth pushing pollen into the stigma
tube of the yucca flower while visiting the
flower to deposit her eggs.
 Predatory-prey coevolution
I. One common example is the relationship
between some species of birds and
butterflies.

Parasite-host coevolution
 One organism lives on other organism
harming it and possibly causing death.
 The parasite live on or in the body of the
host
 Maize plant (host) and Oospores (parasite)
 Cor/ Maize disease

Macroevolution
 Descent with modification
 The process by which modern organism have
descended from ancient ancestor due to many small changes
over millions years (Long time)
 macroevolution describes patterns on the tree of life at a
grand scale across vast time periods.
 Many different patterns can be observed across the tree of
life at a grand scale , including
• stability
• gradual change
• rapid change
• adaptive radiations(Divergent evolution)
• extinctions
• the co-evolution of two or more species
• convergent evolution in traits between species

Examples of Macroevolution
 The origin of eukaryotic life forms
 the origin of humans
 the origin of eukaryotic cells
 extinction of the dinosaurs.

Microevolution
 Small changes within a species’s set of genes that result in phenotypic differences
 Decades or centuries (Short time)
 Under certain environmental conditions,can produce new ,closely related
species.
 Variants in color are a form of microevolution
 Microevolution describes mechanisms that alter the frequencies of alleles in
gene pools within species
 These mechanisms include
• mutation
• Migration
• genetic drift
• natural selection

Examples of Microevolution
• Animals adjusting to camouflage is an example of microevolution.

Importance of Pattern of Evolution
 Evolution also helps in promoting biodiversity.
 It leads to speciation, it could lead to a wide range
of different organisms thriving in diverse habitats.
 Divergent evolution allows species with common
ancestral origin to be able to adapt to their own
habitats.

Pattern of evolution

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Pattern of evolution