Download Reproductive isolation

Chapter 5
Figure 5.2 (a)
Figure 5.2 (b)
Figure 5.3
Figure 5.4 (a)
Figure 5.4 (b)
Figure 5.6 (a)
Figure 5.6 (b)
Species and Speciation
• Fundamental unit of classification is the species.
• Species = a group of populations in which genes are
actually, or potentially, exchanged through
interbreeding.
• Problems
– Reproductive criterion must be assumed based on
phenotype and ecological information.
– Asexual reproduction
– Fossil
– Geographical isolation
Reproductive isolation leads to
Speciation
- the formation of new species
• Requirement
– Subpopulations are prevented from interbreeding
– Gene flow does not occur (Reproductive isolation)
• Reproductive isolation can result in evolution
• Natural selection and genetic drift can result in
evolution
Allopatric Speciation
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geographical isolation
Adaptation to different environments
Genetic drift
Results in members not being able to mate
successfully
• Most common type of speciation
• i.e. Galapagos island Finches
Fig 5.7 Allopatric Speciation:
Geographic barrier divides a population
3 subpopulation of Freshwater fish
A, A1, and A2
Genetic exchange occurs between A and
A1 and between A1 and A2.
Exchanges less likely in A and A2
Rise in water forces the breakup of A1
and makes A and A2 separate
populations.
Genetic drift and different selection
pressures result in B and C
Sympatric Speciation
• Occurs within a single population
• Even though populations are together (sympatric) they
may be reproductively isolated
To demonstrate sympatric speciation
Researchers
• Demonstrate species share a common ancestor
• Arose without geographical isolation
• i.e. studies of indigobirds from Africa
Morphological variation between indigobird
species
Nestling mouth markings in V.
camerunensis (a) and V.
chalybeata (b) mimic the young of
their firefinch hosts, L. rara and L.
senegala, respectively. Dark wing
and plumage in V. chalybeata from
West Africa (c). Pale wing and
green plumage in V. raricola (d).
White bill and blue plumage in V.
camerunensis (e). Red bill and
orange feet in V. chalybeata from
southern Africa (f).
Figure 5.8
Rates of Evolution
Fig 5.1 Speciation of Darwin’s Finches
Warbler
Fig 5.1 (b) Large ground finch
EOC Figure
Opener Chapter 7
Chapter 7
Animal Classification, Phylogeny, and Organization
Common names
• Crawdads, crayfish, or crawfish?
• English sparrow, barn sparrow, or a house sparrow?
Problem with common names
• Vary from region to region
• Common names often does not specify particular species
Binomial system of Nomenclature brings order
to a chaotic world of common names
• Universal
• Clearly indicates the level of classification
• No two kinds of animals have the same binomial name
• Every animal has one correct name International
Code of Zoological Nomenclature
• Genus begins with a Capital letter
• Entire name italicized or underlined
• Homo sapien or H. sapien
Kingdom of Life
1969 R. Whittaker- five kingdom classification
System of classification that distinguished b/w
kingdoms according to
• cellular organization
• mode of nutrition
Monera- bacteria and cyanobacteria are
prokaryotic
• Protista- single or colonies of eukaryotic
cells (Ameoba, Paramecium)
• Plantae- eukaryotic, multicellular, and photosynthtic. Have
cell wall, and usually nonmotile
• Fungi-eukaryotic and multicellular. Have cell wall and
nonmotile. Mode of nutrition distiguishes fungi from plantfungi digest extracellularly and absorb the breakdown
products
• Animalia- eukaryotic and multicellular, usually feed by
ingesting other organisms, cell lack cell walls, and usually
motile
Figure 7.2 (a)
Challenge of the five class system
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Ribosomal RNA excellent for studying evolution
rRNA changes very slow (evolutionary conservation)
Closely related organisms have similar rRNAs
Comparison of rRNA of different organisms
concludes
• All life shares a common ancestor
• Three major evolutionary lineage (domains) and
supersedes the kingdom as the broadest taxonomic
grouping
The three domains
• Arhaea- prokaryotic microbes live in extreme
environments, inhabit anaerobic environments
• Reflect the conditions of early life
• Archaea the most primitive life form
• Archaea give rise to two other domains
– Eubacteria- true bacteria and are prokaryotic
microorganisms
– Eukarya- include all eukaryotic organisms, diverged
more recently thus more closely related to archae
(protists, fungi, plants and animals)
Figure 7.2 (b)
Text devoted to animals
• Except for Chapter 8 Animal like protists (Amoeba
and Paramecium)
• The inclusion of protozoa is part of a tradition
• Once considered a phylum (Protozoa) in the animal
kingdom
Pattern of Organization
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Symmetry
Asymmetry
Radial symmetry
Bilateral symmetry
Figure 7.7 Asymmetry red encrusting sponge
Figure 7.8
Radial symmetry tube coral pulp
Part 2
Acoelomate Bilateral Animals
• Consist of phyla:
– Phylum Platyhelminthes
– Phylum Nemertea
– Others…
Bilateral animals
• Bilateral symmetry = important evolutionary
advancement
– Important for active, directed movement
• Anterior, posterior ends
– One side of body kept up (dorsal) vs. down (ventral)
Directed movement evolved with anterior sense organs
cephalization
Cephalization
– specialization of sense organs in head end of animals
Bilateral Symmetry
• Divided along sagittal plane into two mirror images
– sagittal= divides bilateral organisms into right and left
halves
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Anterior= head end
Posterior= tail end
Dorsal= back side
Ventral= belly side
• Symmetry, fig. 7.9
– Median= sagittal
Other Patterns of Organization may reflect evolutionary
trends
• Unicellular (cytoplasmic)- organisms consist of single
cells or cellular aggregates,
– provide functions of locomotion, food acquisition,
digestion, water and ion regulation, sensory perception
and reproduction in a single cell.
– Cellular aggregates consist of loose association, cells that
exhibit little interdependence, cooperation, or
coordination of function
– Some cells may be specialized for reproduction, nutritive
or structural function
• Diploblastic Organization
– Cells are organized into tissues in most animal phyla
– Body parts are organized into layers derived from two
embryonic tissue layers.
– Ectoderm- Gr. ektos, outside + derm, skin gives rise to
the epidermis the outer layer of the body wall
– Endoderm- Gr. Endo, within, gives rise to the
gastrodermis that lines the gut
Mesoglea- between the ecto and endo and may or may not
contain cells
– Derived from ecto and/or endo
– Cells form middle layer (mesenchyme)
– Layers are functionally inderdependent, yet cooperate
showing tissue level organization i.e. feeding movements
of Hydra or swimming movements of a jellyfish
Figure 7.10
The Triploblastic (treis, three +blaste, sprout)
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Animals described in chapters 10-22
Tissues derived from three embryological layers
Ectoderm- outer layer
Endoderm- lines the gut
• Mesoderm- meso, middle, Third layer between Ecto
and Endo
– Give rise to supportive cells
Figure 7.11
• Most have an organ system level of organization
• Usually bilaterally symmetrical or evolved from
bilateral ancestors
• Organized into several groups based on the presence
or absence of body cavity and for those that posses
one, the kind of body cavity present.
• Body cavity- fluid filled space in which the internal
organs can be suspended and separated from the body
wall
Body cavities are advantageous
1. Provide more room for organ development
2. Provide more surface area for diffusion of gases,
nutrients, and waste into and out of organs
3. Provide area for storage
4. Often act as hydrostatic skeletons (supportive yet
flexible)
5. Provide a vehicle for eliminating wastes and
reproductive products from the body
6. Facilitate increase in body size
What does acoelomate mean?
No coelom
Acoelomate a, without+ kilos, hollow
• Mesoderm relatively solid mass
• No cavity formed between ecto and endo
• These cells within mesoderm often called
parenchymal cells
• Parenchymal cells not speciallized for a particular fnc.
What’s a coelom?
• coelom=
– true body cavity
– Fluid-filled
– lined by mesoderm-derived epithelium
Earthworm
• Acoelomates lack a true body cavity
– Solid body
– no cavity b/w the digestive tract and outer body wall
Do these questions now…
• Think about aceolomate bilateral animals:
– To what domain do they belong
– “ ” kingdom ” ” ”
– What phyla include these organisms
• What is bilateral symmetry, and why was it an
important evolutionary advantage
movie
Acoelomate Bilateral Animals
1.
Simplest organisms to have
bilateral symmetry
2.
Triploblastic
3.
Lack a coelom
4.
Organ-system level of
organization
5.
Cephalization
6.
Elongated, without
appendages
Reproductive and
osmoregulatory systems
Acoelomate Bilateral Animals
1.
Simplest organisms to have
bilateral symmetry
2.
Triploblastic
3.
Lack a coelom
4.
Organ-system level of
organization
5.
Cephalization
6.
Elongated, without
appendages
Reproductive and
osmoregulatory systems
Triploblastic Pseudocoelomate pseudes, false
• Body cavity not entirely lined by mesoderm
• No muscle or connective tissue associated with gut
• No mesodermal
The Triploblastic Coelomate Pattern
• Coelom is a body cavity completely surrounded by
mesoderm
• Peritoneum- mesodermal sheet that lines the inner
body wall and serosa (outer covering of visceral
organs)
• Having mesodermally derived tissue (muscle,
connective tissue) enhances the function of all internal
body systems.
Figure 7.12
Figure 7.3
Groups traced to separate ancestors
All descendants of a single ancestor
Includes some but not all of a members of a lineage
Fig 7.3 Evolutionary groups
Figure 7.4
Fig 7.4 Vertebrate
Phylogenetic tree depicts
the degree of divergence
from a common ancestor
Figure 7.5
Fig 7.5 Interpreting Cladograms
Five taxa (1-5) and characteristics (A-H)
Symplesiomorphies- common characters in a group
Figure 7.6
EOC Figure