Darwin and Diversity 2 Flashcards
What is biodiversity?
A measure of the variety of life at all levels.
What is biodiversity?
A measure of the variety of life at all levels.
What are the three levels of biodiversity?
Ecosystems, species, genes
What is the order of hierarchal classification?
Kingdoms, Phylums, Class, Order, Family, Genus, Species
What are described species?
Species which have been named and have a published description.
What are undescribed species?
Species which have not been scientifically recognised but are informally recognised as a distinct species.
Approximately how many described species are there?
1 - 2 million
Approximately how many described eukaryotic species are there?
~1.8 million
What is the most recent estimate of the number of eukaryotic species, including undescribed species?
8.7 ± 1.3 million
What does a species scape do?
Ranks groups of organisms according to their relative contribution to biodiversity.
How much of the worlds animal biodiversity do birds and mammals make up?
~2%
How much of the worlds animal biodiversity do insects make up?
~75%
What are biodiversity hotspots?
Areas which contain unusually large amounts of biodiversity.
How much landmass do all biodiversity hotspots take up?
Where are the biodiversity hotspots?
Usually around the tropics, but also in places like Madagascar and New Zealand.
Why are most biodiversity hotspots around the tropics?
- There is more land of organisms to live on.
- No glaciation occurred so environmental conditions have not been drastically altered
- More energy from sunlight reaches the tropics, enabling more plants to live here
Why are most biodiversity hotspots around the tropics?
- There is more land of organisms to live on.
- No glaciation occurred so environmental conditions have not been drastically altered
- More energy from sunlight reaches the tropics, enabling more plants to live here
What are the three levels of biodiversity?
Ecosystems, species, genes
What is the order of hierarchal classification?
Kingdoms, Phylums, Class, Order, Family, Genus, Species
What are described species?
Species which have been named and have a published description.
What are undescribed species?
Species which have not been scientifically recognised but are informally recognised as a distinct species.
What is an animal? (3)
- multicellular
- heterotrophic
- eukaryotic
Approximately how many described eukaryotic species are there?
~1.8 million
What is the most recent estimate of the number of eukaryotic species, including undescribed species?
8.7 ± 1.3 million
What does a species scape do?
Ranks groups of organisms according to their relative contribution to biodiversity.
How much of the worlds animal biodiversity do birds and mammals make up?
~2%
How much of the worlds animal biodiversity do insects make up?
~75%
What are biodiversity hotspots?
Areas which contain unusually large amounts of biodiversity.
How much landmass do all biodiversity hotspots take up?
Where are the biodiversity hotspots?
Usually around the tropics, but also in places like Madagascar and New Zealand.
How much biodiversity do biodiversity hotspots contain?
Around a third of all plants, amphibians, birds, reptiles, and mammals.
Why are most biodiversity hotspots around the tropics?
- There is more land of organisms to live on.
- No glaciation occurred so environmental conditions have not been drastically altered
- More energy from sunlight reaches the tropics, enabling more plants to live here
What is the relationship between body size and diversity?
Biodiversity is inversely proportional to size.
There is less diversity among very large animals, as they require a lot of energy and tend to overheat.
It seems that there are also very few organisms
How many organisms
up to 100 million
What is the Shannon Diversity index (H) used for?
To measure the biodiversity in an area.
What is the Shannon Diversity Index?
∑(p_n ln(p_n)) when p_a, p_b. . . are the different species in an area
What does a large value on the Shannon diversity Index mean?
Large amounts of biodiversity
What is an animal? (3)
- multicellular
- heterotrophic
- eukaryotic
What type of tissues do animals have?
Tissues which develop from embryonic layers
Which two characteristics are conserved among animals?
- production of collagen
* possession of Hox genes, especially the Homeobox sequence
What is symmetry?
A correspondence in the size and shape of body parts on opposite sides of a median plane.
What is radial symmetry?
Symmetry through two or more planes through the longitudinal axis.
What is the body structure of radially symmetrical organisms?
They have an oral (mouth) and aboral (no mouth) end.
What is the advantage of radial symmetry?
It enables organisms to meet the environment equally well from all directions, so is highly beneficial to stationary organisms.
What is bilateral symmetry?
Symmetry along the bilateral plane.
What is the body structure of bilaterally symmetrical organisms?
They have a right and a left side.
What is cephalisation?
The concentration of the sensory structures at the head end of the organism.
Who is cephalisation beneficial for?
Organisms which move a lot in one particular direction, such as predators and fleeing prey.
What type of organisms are cephalisation found in?
Bilaterally symmetrical organisms.
What is gastrulation?
The infolding of the blastula to for the archenteron and germ layers.
What is the archenteron?
An deep, narrow, blind-ended tube which develops into the digestive tract.
What is the blastopore?
The opening of the archenteron.
What are the three germ layers?
endoderm, ectoderm, mesoderm
What does the endoderm develop into?
gut, liver, and lungs
What does the ectoderm develop into?
skin
What does the mesoderm develop into?
muscles and other organs
Which germ layers do diploblastic embryos have?
endoderm and ectoderm
How do diploblastic animals move?
Diploblastic embryos don’t have a mesoderm, so the developed animal does not have muscles. They move by contractile elements in their skin.
What is the oldest phylum?
Porifera (sponges)
Describe the body structure of porifera.
They don’t have true tissues, organs, or a nervous system. Instead, they are made up of a gelatinous matrix which is supported by a skeleton-like array of minute spictules.
What form of symmetry do Porifera have?
They have no symmetry.
How do Porifera reproduce?
They can reproduce both sexually and asexually.
Which genus has an osculum?
Porifera
What is an osculum?
A hollow cavity which connects the inner layer of cells in sponges to the external environment.
What are coanocytes?
Flagella-like structures found on Porifera.
What is the function of the coanocytes?
- pull water through pores to the osculum
* pass food particles to cells within the sponge
What are four animals in the Phylum Cnidaria?
anemones, corals, jellyfish, and hydra
Describe the structure of animals in the phylum Cnidaria.
Diploblastic and radially symmetrical. They have a gastrovascular cavity with a single opening.
What are the two forms of Cnidaria, and give examples of these two forms.
There are Polyps and Medusa. Anemones and corals are polyps, and jellyfish and hydra are medusa.
What are the three clades within Bilatera?
•Lopotrochozoa
*Ecdysozoa
•Deuterostomia
What is the defining characteristic of animals in the clade Bilatera?
Bilateral symmetry
What are the two defining characteristic of animals in the clade Lophotrochozoa?
- Lophophores
* Trochophores
What are Lophophores?
A ray of feeding tentacles which act as the animals feeding structure.
What are Trochophores?
A developmental stage which only Lophotrochozoans pass through.
What is the defining characteristic of animals in the clade Ecdysozoa?
A tough cuticle which is moulted as the animal grows.
What are the three types of body cavity?
- Coelomates
- Pseudocoelomates
- Acoelomates
Describe the body cavity of a coelomate.
A coelum within the mesoderm which is fully lined by the mesoderm.
What is the advantage of a coelom?
It enables organs to move independently of the organism.
Describe the body cavity of pseudocoelomate.
A coelum which lies between the mesoderm and the ectoderm. It is only partially lined by the mesoderm.
Describe the body cavity of a acoelomate.
They don’t have a body cavity.
What are the two developmental modes?
Deuterostomal development and protostomal development.
What pattern of cleavage do protostomes have?
Spiral, determinate cleaveage
What pattern of cleavage do deuterostomes have?
Radial, indeterminate cleavage
What is determinate cleavage?
When the fate of every cell in an early embryo is determined.
What is indeterminate cleavage?
When the fate of cells in early embryos is not determined and each cell during early cleavage has the ability to develop into a complete embryo.
How is the coelom formed in protostomes?
From splits in solid masses of the mesoderm.
How is the coelom formed in deuterostomes?
From pockets of mesoderm which bud off the archenteron.
What does the blastopore develop into in protostomes?
The mouth
What does the blastopore develop into in deuterostomes?
The anus
What are the developmental patterns of deuterostomes?
- radial, indeterminate cleavage
- coelom formed from pockets off the archenteron
- blastopore becomes the anus
What are the developmental patterns of protostomes?
- sprial, determinate cleavage
- coelum forms from solid masses of mesoderm
- blastopore becomes the mouth
What are the three main phyla in the Clade Lophotrochozoa?
- Platyhelminthes (flatworms)
- Mollusca
- Annelida (segmented worms)
Describe the body structure of Platyhelminthes.
Solid, acoelomatic creatures. They have a digestive cavity with a single opening which doubles as a mouth and an anus and moderate cephalisation.
Describe the circulatory system of Platyhelminthes.
Platyhelminthes do not have any blood or haemoglobin. They are thin and flat enough to be able to diffuse gases directly between the cells and the environment. They have no circulatory system.
Describe the development of Platyhelminthes.
Platyhelminthes have triploblastic development and an organ system level of organisation.
What are the three major classes of Platyhelminthes?
- free living flatworms
- parasitic tapeworms
- (usually) parasitic flukes
How do Platyhelminthes get nutrients to cells without a circulatory system?
They have branches off their gastrovascular cavity which carries nutrients to cells.
What are three animals within the phylum Mollusc?
slugs, snails, and squid
Describe the body structure of Molluscs.
Mollsucs have a visceral mass which contains most of their organs. This is covered by the mantle, which is a fold of tissue and may also excrete a skull. They have a muscular foot for movement.
Describe the digestive system of Molluscs.
Molluscs have a one way digestive tract with a single opening.
Describe the circulatory system of Molluscs.
Molluscs have an open circulatory system. Hemolymph in the coelom is pumped around the gills to become oxygenated. It then goes to sinuses around the organs so that oxygen is delivered to the cells.
What are two examples of animals in Annelida?
Segmented worms such as leeches and earthworms.
Describe the body structure of Annelids
Segmented (metamersim) worms with circular and longitudinal muscles. They are coelomates, and have chitinous chaetae (tough, bristly protrusions).
Describe the circulatory system of Annelids.
Closed circulatory system.
What are the two main phyla in the Clade Ecdysozoa?
Nematoda and Arthropoda
How are Nematodes different to Annelids?
Nematodes are round worms, so they only have longitudinal muscles and are not segmented.
Describe the digestive system of Nematodes.
Nematodes have a complete digestive tract.
Describe the circulatory system of Nematodes.
Nematodes do not have a circulatory system. Instead, they use pseudocoelomic fluid to transport nutrients to cells.
What is the defining feature of Nematodes?
They are defined by a tough, transparent, non-living cuticle which they grow, shed, and regrow throughout their life.
How do Nematodes reproduce?
Sexual reproduction.
Comment on the diversity of Nematodes.
Nematodes are extremely diverse with a huge environmental range. It is estimated that every plant and animal species has a specific Nematode predator.
What are some examples of animals in the phylum Arthropoda?
Spiders, insects, and flies
Comment on the diversity of Arthropoda.
It is estimated that 2/3 of all animal species belong to Arthropoda.
Describe the body structure of Arthropods.
Triploblastic, bilateral, segmented animals with paired, jointed limbs. They have a rigid exoskeleton.
What is the function of the exoskeleton in Arthropoda?
- support
* dessication prevention
Describe the circulatory system of Arthropoda.
Arthropods have an open circulatory system where hemolymph is pumped to the sinuses to deliver oxygen etc to cells.
What are the two main phyla within Deuterostomia?
Echinodemata and Chordata
What are two animals in the phylum Echinodemata?
Starfish and sea urchins.
Describe the symmetry of Echinodemata.
They have a loose degree of radial symmetry as adults, but are bilaterally symmetrical when developing.
Describe the structure of Echinodermates.
They are slow moving marine animals. Their extensive coelom forms a water vascular system, which is used to form a water vascular system.
Describe the structure and function of the water vascular system in Echinodemata.
The water vascular system is a network of hydraulic canals which form from the coelom. It branches into extensions called tube feet, which are used for feeding and locomotion.
What are the three main clades within Echinodemata?
- Asteroidea
- Echinoidea
- Holothurcidea
What is an example of an Asteroidean?
starfish
Describe the structure of Asteroidea.
- tube feet
- ventral mouth
- arms extending from a central disk
How do Asteroidea eat?
They eat bivalves by ejecting their stomach and digesting them outside the body.
What is an example of an Echinodean?
Sea urchin
Describe the structure of Enchinodea.
- five rows of tube feet
- spines (used for locomotion)
- no arms
How do Echinodea eat?
They eat seaweed with a complicated jaw structure called Aristotle’s Lantern.
What is an example of a Holothurcidean?
sea cucumbers
Describe the structure of Holothurcidea.
- five rows of tube feet
- no spines
- no arms
- reduced endoskeleton
- usually have feeding tentacles
What are the defining characteristics of Chordates?
- notochord (stiffens animal)
- hollow, dorsal, nerve cord
- pharyngeal slits
- post-anal, muscular tail (may only be in embryos)
What is the main subphylum in Chordata?
Vertebrata
What are the five main classes within vertebrata?
- Chondrichthyes
- Actinopterygii
- Amphibia
- Reptilia
- Mammalia
What is an example of a Chondrichthyes?
sharks
What are the main features of Chondrichthyes?
- cartilaginous endoskeleton
- 5 - 7 gill slits
- no swim bladder
What effect does the lack of a swim bladder in Chondrichthyes have?
It means that they can’t control their depth, so they sinnk if they stop swimming.
What is an example of an Actinopterygii?
ray finned fish
What are the main features of Actinopterygii?
- ossified skeleton
- swim bladder
- one gill slit which is covered by an operculum
What is an example of an Amphibian?
frogs
What are the main features of amphibians?
- ectothermic
- tetrapods
- have moist skin with mucus glands instead of scales
What are examples of Reptiles?
birds, lizards, and snakes
What are the main features of reptiles?
- ectothermic
- tetrapods
- dry, scaly skin
- lungs and ribs
Describe how reptiles develop from embryos.
Reptiles don’t have a larval stage. Instead, they have a shelled amniotic egg which they lay on land.
How are birds different to other reptiles?
- endothermic
* feathers (but still scales on feet)
What are the main features of mammals?
- endothermic
- tetrapods
- mammary glands
- hair
What are the three main mammal lineages?
- monotremes
- marsupials
- eutherians
How do monotremes reproduce?
lay eggs
How do marsupials reproduce?
pouch
How do eutherians reproduce?
placental, so offspring develops inside the mother.
