Pertemuan ke-7 Adaptasi

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Pertemuan ke-7Adaptasi

• Oleh Dwi Kusuma Wahyuni, S.Si., M.Si.
• Departemen Biologi Fakultas Sains dan Teknologi
  Universitas Airlangga

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Sub Topik

• Adaptasi dan Fungsinya
• Adaptasi dan kecepatan Evolusi
• Evolusi Adaptasi

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Kaitan Seleksi Alam dan Adaptasi
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• Proses Seleksi Alam dan Adaptasi
  didiskripsikan sebagai survival of the fittest

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Pengertian Adaptasi

• 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.

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Contoh adaptasi ????
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Evolusi Adaptasi kompleks

• Adaptasi terjadi pada semua struktur komplek.
  Adaptasi memerlukan waktu yang lama sebagai hasil
  dari adaptasi-adaptasi kecil.
• 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.
• Perubahan struktur menjadi organ komplek memberi
  keuntungan pada organisme dan diturunkan pada
  keturunannya

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Evolution of the Human Eye
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Fungsi adaptasi??????
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Perubahan Fungsi Adaptasi

• Kadang-kadang adaptasi yang melibatkan satu
  fungsi yang bermakna. Ini disebut exaptation.
• Contohnya???????

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Evolusi Ekstremitas Superior dan Jari-Jari
Vertebrata Terestrial

• Pada organisme aquatik digunakan untuk bergerak
  mengelilingi lingkungannya. Digunakan untuk
  bergerak pelan dan cepat dll. Seperti organisme
  berpindah ke darat untuk hidup
• Selanjutnya adaptasi tersebut berguna untuk hidup
  di darat.

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Ilustrasi Evolusi Ekstremitas Superior
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Tipe-tipe Adaptasi

• Tiga tipe adaptasi
• Struktur
• Fisiologi
• Perilaku

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Adaptasi Struktur

• Adaptasi yang mempengaruhi kenampakkan, bentuk,
  atau pengaturan partikel-partikel kenampakan
  fisik, termasuk didalamnya adalah mimikri dan
  kamuflase (cryptic colouration).
• Mimikri suatu spesies meniru spesies yang lain
  atau bagian dari spesies yang lain.
• 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

• Learning about adaptations in mole-rats can help
  you understand how natural selection has affected
  them.

• The ancestors of todays common mole-rats
  probably resembled African rock rats.

Section 15.1 Summary pages 393-403
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Structural adaptations arise over time

• Some ancestral rats may have avoided predators
  better than others because of variations such as
  the size of teeth and claws.

Section 15.1 Summary pages 393-403
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Structural adaptations arise over time

• Ancestral rats that survived passed their
  variations to offspring.

• After many generations, most of the populations
  individuals would have these adaptations.

Section 15.1 Summary pages 393-403
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Structural adaptations arise over time

• Over time, natural selection produced modern
  mole-rats.

• Their blindness may have evolved because vision
  had no survival advantage for them.

Section 15.1 Summary pages 393-403
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Structural adaptations arise over time

• 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.

Section 15.1 Summary pages 393-403
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Caterpillar mimics Bird droppings
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Structural adaptations arise over time

• 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.

Section 15.1 Summary pages 393-403
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Kamuflase

• 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
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Adaptasi Fisiologi

• Adaptasi yang berasosiasi dengan fungsi-fungsi
  organisme.
• Contoh-contohnya?????

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Adaptasi Perilaku

• Adaptasi yang diasosiasikan dengan bagaimana
  bagaimana organisme merspon lingkungannya.
• Contoh
• 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

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Apakah Evolusi Menuju Kesempurnaan??

• Meskipun banyak orang mengira bahwa adaptasi dan
  seleksi alam bertendesi membuat organisme
  sempurna but this is not the case.
• Adaptasi dan seleksi alam menyederhanakan
  perubahan suatu organ atau organisme pada jalur
  yang memperbaiki kesempatan untuk bertahan hidup
  di dalam lingkungannya

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Why Evolution Is Not Perfect

• 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.

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Adaptive Radiation I

• The diversification of a common ancestral species
  into a variety of species is called adaptive
  radiation.
• Darwins 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.

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Darwins Finches Adaptive Radiation
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Adaptive Radiation II

• 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 Earths history.

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Divergent Convergent Evolution

• Divergent evolution
• 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
• Two unrelated species develop similar traits
  after developing independently in similar
  environmental conditions.

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Phylogenetic Tree shows Divergence
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Co-evolution

• 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
• 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.

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Co-evolution Examples
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Pace of Evolution

• Two models attempt to explain the rate of
  evolutionary change
• Gradualism
• 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
• evolutionary change consists of long periods of
  stasis (equilibrium) or no change interrupted by
  periods of rapid divergence or change.

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Kesimpulan