Pre christmas Flashcards
What is the biological species concept and what are its associated problems?
Its a definition of a species:
A group of actually or
potentially breeding natural
populations that are
reproductively isolated from
other groups
Problems:
* Not applicable to asexually reproducing organisms
* Cant tell if fossils could reproduce
* Borderline cases like crows where they overlap, is difficult to establish if produce fertile offspring or not
What is the phenetic species concept, and what are the problems associated it ?
Problems:
* Genotypes dont produce fixed phenotypes like in the case of Ecophenotypes
* Cryptic species and sibling species
* Some fossils look the same
What is cladistics?
A method of hypothosising the reationships between organisms based on uniquely shared characteristics or traits
What is paraphyletic and polyphyletic?
Paraphyletic:
(of a group of organisms) descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
Polyphyletic:
(of a group of organisms) derived from more than one common evolutionary ancestor or ancestral group and therefore not suitable for placing in the same taxon:
Define
Synapomorphy
Plesiomorphy
Synapomorphy: A shared, derived character state. This is an apomorphy that two taxa share and that is assumed to have been present in the common ancestor of those two taxa. An example would be feathers in birds. All birds have feathers
Plesiomorphy: An ancestral character state. This is any trait that was inherited from the ancestor of a group. For example, reptiles are exothermic, they do not maintain a constant internal body temperature. They have this characteristic because the ancestor of all reptiles was exothermic. This differs from a synapomorphy because some descendants of the first reptiles are not exothermic (birds are endothermic). In other words, this trait is ancestral, but is shared by some, but not all, of that ancestors; descendants.
Analogous vs homologous
Homo - same evolution orgin trait
anal - diff, but looks similar
Exaption
When a feature has been coopted to serve a new function
What are the metazoa and what are the 5 clades within this grouping?
- Kingdom consisting of Animalia
- A monophyletic group
Common characteristics:
* Multicellular
* Specialisation of tissues
* Motility
* Heterotrophy
Sexual reproduction
Describe Porifera
Part of the Metazoan kingdom
AKA Sponges
Anatomy
* Choanocytes line the cavities inside
* Choanocytes generate water flow and filter feed
Microscopic spicules are part of the structure of sponges
Describe Ctenophore
- Ctenophora is the sister group to other animals according to phylogenomic studies
- Motility from cilia
- Radial symmetry
- Diploblastic, both mouth and anus, through gut
- Combs of Cilia called Ctenes
Describe Cnidaria
- Part of Metazoan Clade
- Anthozoa and Medusozoa
- Diverse, jelly fish anemones and corals
- Characterised by stinging cells called cnidocysts
- Radial symmetry
Cnideria all have a life cycle involving a sexual medusa stage, mobile planula larval stage and a sessile budding stage - They differ in which part of the life cycle forms the adult
Describe placozoa
- part of metazoan clade
What is long branch attraction?
- Long branch attraction (LBA) is a phenomenon in phylogenetic analyses when rapidly evolving lineages are inferred to be closely related, regardless of their true evolutionary relationships. The problem arises when the DNA of two (or more) lineages evolve rapidly.
- Due to site heterogeneity where bases mutate at different rates, the ones which mutate faster may then confuse genetic analysis by making two species look more similar
List as many of the findings from the burgess shale
Ctenophore
Porifera
Cnidaria
Annelida
Mollusc
Priapulida - Ottola (penis worm)
Oncychophora - Halluciniga (spines on back)
Arthropoda
Deuterostomia
What was the burgess shale?
After a long period of relative stasis in the ediacaren, a rapid diversification appeared in the fossil record. The burgess shale exemplified this. Characterised by ‘weird wonders’
- rapid sea cliff collapse
- low sulfur and high alkalinity
These have been found in the burgess shale. Recall some characteristics.
Ctenophore
Porifera
Cnidaria
Annelida
Mollusc
Priapulida - Ottola
Oncychophora - Halluciniga
Arthropoda
Deuterostomia
Annelida
- Worm like segmentation
- Bristles for motility
Mollusc
- Large foot and radula
- split into several classes including Bivalvia, Gastropoda, Cephalopoda.
Priapulida - Ottola
- Preserved burrows
- U shaped gut
Oncychophora - Halluciniga
- Lobed limbs and spikes
Arthropoda
- Trilobites, preservation of antanae and legs
- Waptia, advanced compound eyes and legs
Deuterostomia
- Anus before mouth development
- Potential for hemichordates and Ecinoderms
- Hemichordates: triploblastic , enterocoelomate and bilaterally symmetrical marine deuterostome animals
- Echinoderms: most asexual and most 5 point radial symmetry
Deuterostomia: Metaspriggina
* Paired eyes
* Msucles on back
* Gill arches
* Chordate affinity
* A vertebrate! Closest cambrian relative
* Usefull for dispalying evolutionary points
Differentiate between stem and crown group
Crown group is a monophyletic group containing the living species down to their last common ancestor
Stem group is the last common ancester and its descendants excluding those alive today
What was the burgess shale?
After a long period of relative stasis in the ediacaren, a rapid diversification appeared in the fossil record. The burgess shale exemplified this. Characterised by ‘weird wonders’
What was the burgess shale?
After a long period of relative stasis in the ediacaren, a rapid diversification appeared in the fossil record. The burgess shale exemplified this. Characterised by ‘weird wonders’
What are the lophotrochozoa?
A very diverse clade of protosome animals within the spirilia.
What are the lophophore and trochophore?
Trochophore
* Larval stage for many of the lophotrochozoan clade.
* Characterised by bands of cillia and testicles for motilitity and feeding.
Lophophore
* Feeding apparatus that extends out
* used by many of the lophotrochozoans
What are the Bryozoa?
The moss animals
Phyla of lophotrochozoa
* Resemble aquatic plants, some individuals called Zoids for feeding, some for defence, division of labour, connected by a web of tissue
https://www.digitalatlasofancientlife.org/learn/bryozoa/
What are Entoprocta?
Superficially similar to bryozoa (ectoprocta). Lophotrochoza.
- Colonial
- Feeding crown not technically lophophore
Goblet animals
What higher phyla are the cycliophora apart of?
These are the ones which live in the mouth of a lobster.
Lophotrochozoa
What are the Gnathifera?
Rotifera: Thorny-headed worms, live in soil, spin their mouth parts
Micrognathizoa: Jaw animals, complex jaw, lay eggs
Gnathostomulida: Jaw Worms, eggs burst out their body
What phyla are the platyhelminthes in?
Lophotrochozoa
- contain flatworms, flukes and tapeworms
- Regenerative, some parasitic
- Bilateral
What are the Brachiopoda
- Bivalve appearance but lophophore inside
Lots in the palaeozoic
Lophotrochozoa
What are the Phoroniada (horseshoe worms)
Pretty sure the things that dissapear when you click.
* Phoronida - Have larvae - Bore into substrate - Filterfeed Horseshoe worms
What are the nemertae?
Lophotrochoza ribbon worms
Who are the freakin annelids am right!?
- Segmented
- Repeated segments of the body with ITS own organs and function
- Important ecological functions
Contain:
- Polychaetes, have bristles, diverse, predators to filter-feeders
- Clitellates, leeches, earthworms
What phyla do the mollusca belong to?
Lophotrochoza
- Diverse inside, giant squid, very small things
- Herbiverous,
- Emerged in mid cambrian
- Mainly marine, 23% all described marine organisms
Contain:
- gastropods
- cephlapods
What is the ecological importance of the annelids?
- Aeration
- Fertilisation
- Drainage
- Prevents compaction
What are the subphyla of the arthropods?
- Trilobites
- Chelicerates
- Mandibulates
What orders make up the Sub phyla chelicerata?
Contains orders:
- Meristomate
- Arachnida
-pycnigoda
What are Arthropoda characteristics?
- Segmented
- Jointed apendages
- Open circulatory system
- Moulting exoskelton
- Cephalized
Often sexually dimorphic
Who are the merostomata?
A class of Chelicerate containing:
The sea scorpions (Eurypterida)
- predatory
- known for gigantism, linked to the rising sea levels
Horseshoe crabs (Xiphosurida)
- Hemocyanin in blood
- compound eyes
Who are the Pycnognida?
A class in the Chelicerata.
- Sea spiders
- Parental behaviour, father
predatory
Describe the phylogeny of Arachnida.
A Class belonging to the subphyla Chelicerata.
Contain Order:
- Trigonotarbida (extinct)
* Araneae
* Opiliones
* Solifugae
* Scorpions
* Theyliphonda
* Amblypygi
- Acari
Describe the Order Trignotarbida
Trigonotarbida (class Arachnida)
* One of first to go to land
* Small around 4mm
Found in rhiney chert
Describe the order Araneae
- Aranae (class Arachnida)
- All but one obligate predator
- Silk production
- 40,000 species
Describe the Order Opiliones
- Opiliones (class Arachnida)
- One body section ish
- Can loose a leg if attacked
- known as harvestmen spiders
predator
Chew their food
Describe the Order Scorpiones
- Scorpiones (class Arachnida)
- Dominate arid predatory environments
- Very slow metabolism
- Some species can survive a whole year without food
- Generalists
Parental care, maternal
Describe the Order Theylyphonida (whip Scorpiones)
Theylyphonida (class Arachnida)
* ‘Whip scorpioins’
* Produce vinegar like chemical defense
* Tropical areas
Carniverous
Describe the Order Amblypygi (tailless whip scorpions)
Amblypygi (class Arachnida)
* Tailess whip scorpions
* Tropical
* Up to 70 cm legspan
* No silk or venom
Describe the order Acari
Acari (class Arachnida)
* Over 50,000 described species
* Million in one litre of lead litter
Fusion of abdomen
Describe the class Pycnogonid
Known as the sea spiders
* Structure called a Chelifore for feeding
- Carry eggs in a suck under the trunk
What are the mandibulates?
A clade of arthropods
Comprises the subphyla Myriapoda (millipedes and others), Crustacea and Hexapoda (insects and others).
What are the class Diploda
Millipedes and such
- A class within the Myriapoda, within the mandibulates
- two sets of legs per body segment
- decomposers
- body section 7 is used to transfer spermatophores
Describe the class Chilopoda
A Class within the Mandibulates, myriapods
* Chilopoda (centipedes)
* One set of legs per body segment *Predators
* Venomous fangs in front legs
* parental care
Within which grouping are the sub phyla crustaceans apart of?
The Mandibulates, along side myriapods and hexapods.
Describe the morphology of crustaceans
- Head
- Thorax
- Abdomen
- Soft bodies with hard calciocarbonate exoskeleton, or kitonous exoskeleton
- Shed for growth
- Legs for walking, for swimming, for defense
- Multijointed/biramous appendage
- Two antenna
- Larval stage, not every group
- Compound eyes
Are Crustaceans monophyletic or paraphyletic?
Paraphyletic
* some crustaceans are more related to other clades than their own according to genetic analysis
Describe the Order Isopoda
Part of the Crustacean sub phyla
- Terrestrial isopods woodlice
- Need humid environments as no cuticular cover
- lots scavengers
- some abisilgigantism (deep sea)
- some parasites
Describe the order decapoda
- lobsters
- Crabs
- Cray fish shrimp
- crab shape evolved 5 times, is a flexible shape for colonising habitats
- Part of the Crustacean taxon
Who are the Cirripedia?
Barnacles
* part of the Crustacean sub phyla
* Planktonic larval stage, unique to crustaceans
Describe the echinoderms
They are deuterostomes
- 5 point radial symmetry, shown to be a specialisation due to their bilateral larval stage
- star fish, sea urchins, sea cucumbers etc
What is cephalisation?
Concentration of nerves and sensory organs at the anterior (like our head)
What is the blastula?
A hollow ball of cells produced during the development of an embryo. Develops in the gastrula via invagination.
* Ectoderm, external layers * Endoderm, internal layers like gut lining * Mesoderm, between layers
What is the difference between a diploblastic and a triploblastic embryo?
Triploblastic has a mesoderm
Goes onto produce:
* Cardiac muscle
* Skeletal muscles cells
* Tubule cells of kidneys
* Red blood cells
* Smooth muscle
What does the presence of a mesoderm in the ctenophores suggest about the evolution of mesoderm?
- Ctenophore have classic mesoderm
- Nerve tissues, circulatory structures and muscles characteristics of triploblastic body plan
- If ctenophore is branches off early in the phylogenetic tree,
Then there must be two origins of mesoderms or multiple losses of mesoderms + all associated structures
What gave rise to bilatarian mesoderm?
Cnidarians
* Classic diploblast body
* Traditionally Inside layers of cnidarian endoderm gave rise to bilaterian mesoderm/ectoderm
Actually comes from the pharyngal area
In triploblastic body plans, there are three different levels of organisation with respect to the presence/ lack of a coelom.
Define Coelum and state the three levels