Transcript Chapter 21 Adaptation & Speciation

Pertemuan ke-7
Adaptasi
Oleh: Dwi Kusuma Wahyuni, S.Si., M.Si.
Departemen Biologi Fakultas Sains dan
Teknologi Universitas Airlangga
Sub Topik
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Adaptasi dan Fungsinya
Adaptasi dan kecepatan Evolusi
Evolusi Adaptasi
Kaitan Seleksi Alam dan Adaptasi
Proses Seleksi Alam dan Adaptasi
didiskripsikan sebagai survival of the fittest
Pengertian Adaptasi
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Adaptasi adalah setiap sifat yang
meningkatkan kecocokan organisme atau
meningkatkan peluang untuk bertahan hidup
dan bereproduksi dengan sukses.
Adaptasi timbul dari seleksi alam.
Lebih dari satu periode waktu, organisme
individual menjadi beradaptasi terhadap
lingkungannya
Karakteristik hasil adaptasi akan diturunkan
pada keturunannya.
Contoh adaptasi ????
Evolusi Adaptasi kompleks
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Adaptasi terjadi pada semua struktur komplek.
Adaptasi memerlukan waktu yang lama sebagai hasil
dari adaptasi-adaptasi kecil.
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Contoh dari adaptasi komplek adalah evolusi mata
manusia dari mata oraganisme yang lebih rendah.
Bentuk mata yang komplek hasil dari perkembangan
bertahun-tahun mata sederhana.
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Perubahan struktur menjadi organ komplek memberi
keuntungan pada organisme dan diturunkan pada
keturunannya
Evolution of the Human Eye
Fungsi adaptasi??????
Perubahan Fungsi Adaptasi
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Kadang-kadang adaptasi yang melibatkan satu
fungsi yang bermakna. Ini disebut exaptation.
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Contohnya:???????
Evolusi Ekstremitas Superior dan JariJari Vertebrata Terestrial
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Pada organisme aquatik digunakan untuk
bergerak mengelilingi lingkungannya. Digunakan
untuk bergerak pelan dan cepat dll. Seperti
organisme berpindah ke darat untuk hidup
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Selanjutnya adaptasi tersebut berguna untuk
hidup di darat.
Ilustrasi Evolusi Ekstremitas Superior
Tipe-tipe Adaptasi
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Tiga tipe adaptasi
1.
Struktur
2.
Fisiologi
3.
Perilaku
Adaptasi Struktur
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Adaptasi yang mempengaruhi kenampakkan,
bentuk, atau pengaturan partikel-partikel
kenampakan fisik, termasuk didalamnya adalah
mimikri dan kamuflase (cryptic colouration).
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Mimikri : suatu spesies meniru spesies yang lain
atau bagian dari spesies yang lain.
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Cryptic colouration (kamuflase): membaur
dengan lingkungannya, organisme berkamuflase
dirinya dengan merubah bentuk atau warnanya
Contohnya: ikan naga menyerupai ganggang laut.
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Structural adaptations arise over time
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Learning about adaptations in mole-rats can help
you understand how natural selection has affected
them.
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The ancestors of today’s common mole-rats
probably resembled African rock rats.
Structural adaptations arise over time
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Some ancestral rats may have avoided predators better
than others because of variations such as the size of
teeth and claws.
Structural adaptations arise over time
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Ancestral rats that
survived passed their
variations to offspring.
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After many generations,
most of the population’s
individuals would have
these adaptations.
Structural adaptations arise over time
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Over time, natural selection produced modern
mole-rats.
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Their blindness may have
evolved because vision
had no survival advantage
for them.
Structural adaptations arise over time
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In another form of mimicry, two
or more harmful species
resemble each other.
For example, yellow jacket
hornets, honeybees, and many
other species of wasps all
have harmful stings and
similar coloration and
behavior.
opossum plays possum well
This fence lizard has
adapted to mimic tree
trunk color
Caterpillar mimics
Bird droppings
Structural adaptations arise over time
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In another form of mimicry, two
or more harmful species
resemble each other.
For example, yellow jacket
hornets, honeybees, and many
other species of wasps all
have harmful stings and
similar coloration and
behavior.
Kamuflase
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Camouflage allows
animals to blend with
their surroundings
Tartan Hawkfish – blends with
Bright gorgonian fans
A narrow-headed frog native to
Madagascar, blends with the mud &
Tree trunks in its environment
Adaptasi Fisiologi
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Adaptasi yang berasosiasi dengan fungsifungsi organisme.
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Contoh-contohnya:?????
Adaptasi Perilaku
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Adaptasi yang diasosiasikan dengan
bagaimana bagaimana organisme merspon
lingkungannya.
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Contoh
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2.
3.
4.
Pola Migrasi.
Courtship patterns.
Perilaku makan.
Plant responses to light and gravity.
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Masing-masing tipe adaptasi tidak bekerja
sendiri-sendiri, tapi sangat tergantung satu
dengan yang lain
Apakah Evolusi Menuju
Kesempurnaan??
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Meskipun banyak orang mengira bahwa
adaptasi dan seleksi alam bertendesi
membuat organisme sempurna but this is not
the case.
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Adaptasi dan seleksi alam menyederhanakan
perubahan suatu organ atau organisme pada
jalur yang memperbaiki kesempatan untuk
bertahan hidup di dalam lingkungannya
Why Evolution Is Not Perfect
1.
2.
3.
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Natural selection only edits variations that already exist in a
population. Evolution has to make do with what is created;
the new designs, although better than the old ones, are less
than perfect.
Adaptations are often compromises of what an organism is
ideally aiming to achieve.
Not all evolution is adaptive. Sometimes chance events can
change the composition of a populations gene pool. Those
organisms which survive a chance events do so randomly, not
because they were better than other organisms.
The individuals that do survive are able to reproduce and
pass on their genes to their offspring. Over time the
population will change, hopefully for the better.
Adaptive Radiation I
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The diversification of a common ancestral species
into a variety of species is called adaptive
radiation.
Darwin’s finches are a good example of adaptive
radiation.
The first inhabited a single island. Eventually, the
finches began to inhabit other neighboring islands.
These islands had slightly different environments
from each other and the selective pressures of the
different environments resulted in different feeding
habits and morphological differences for the finches.
Darwin’s Finches & Adaptive
Radiation
Adaptive Radiation II
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Islands are a great environment for studying
speciation because they give organisms the
opportunity to change in response to new
environmental conditions.
Each island has different physical
characteristics which help the process of
adaptive radiation to occur.
Adaptive radiation can also occur after mass
extinction events in the Earth’s history.
Divergent & Convergent Evolution
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Divergent evolution
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Pattern of evolution in which species that were once
similar diverge or become increasingly different from
each other
Divergent evolution occurs when populations change as
they adapt to different environmental conditions.
Convergent evolution
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Two unrelated species develop similar traits after
developing independently in similar environmental
conditions.
Phylogenetic Tree shows Divergence
Co-evolution
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Coevolution occurs when organisms are linked with other
organisms and gradually evolve together.Predators and prey,
pollinators and plants, and parasites and hosts all influence
each others evolution.
Many plants rely on insects and birds to spread their pollen,
this causes the plants to change themselves in ways that will
entice these organisms to come to the plants.
Examples:
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The constant threat of predators can cause prey species to evolve
faster legs, stronger shells, better camouflage, more effective poisons,
etc.
The struggle between parasites and hosts is another example of
coevolution. Parasites such as bacteria, protozoa, fungi, algae, plants
and animals consume their host in order to survive. Thus, the hosts
must develop ways to defend themselves against the predator.
Co-evolution Examples
Pace of Evolution
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Two models attempt to explain the rate of
evolutionary change
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Gradualism
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change occurs within a particular lineage at a slow
and steady pace. According to this model, big
changes occur from the accumulation of many small
changes.
Punctuated equilibrium
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evolutionary change consists of long periods of stasis
(equilibrium) or no change interrupted by periods of
rapid divergence or change.
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