chapter 5. figure 5.2 (a) figure 5.2 (b) figure 5.3
TRANSCRIPT
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
• 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
Geographic barrier divides a population3 subpopulation of Freshwater fishA, A1, and A2
Fig 5.7 Allopatric Speciation:
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 plant- fungi 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
• 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
• 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
• 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)
• 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
Reproductive and osmoregulatory systems
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
Acoelomate Bilateral Animals
Reproductive and osmoregulatory systems
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
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
Fig 7.3 Evolutionary groups
All descendants of a single ancestor
Includes some but not all of a members of a lineage
Groups traced to separate ancestors
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