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--- lecture_notes:04-23-2010 [2010/04/26 18:18]
svasili
+++ lecture_notes:04-23-2010 [2010/05/01 16:00] (current)
jlong Link to Slides of John and Jan
@@ Line 17: / Line 17: @@
 ====== Slides ======
-Jeffrey Long has slides from Janet Leonard and he will be uploading them.\\
+The slides from the presentation of John and Janet can be dowloaded here,[[http://compbio.soe.ucsc.edu/slugGenome/|http://compbio.soe.ucsc.edu/slugGenome/]] .\\
+====== Additional notes ======
+//Additional notes from Jonathan follow.//
+===== John Pearse talk =====
+John originally worked with sea urchins and sea stars primarily.
+Janet joined the lab about twelve years ago to study marine slugs.
+She was interested in hermaphrodite mating behavior.  Banana slugs'
+rare behavior of apophallation became a research focus.  No one had
+really studied banana slugs [academically] since the forties.  Alice
+Bryant Harper (Aptos naturalist, works with Santa Cruz Museum of
+Natural History) wrote __The Banana Slug__ (1988), the best book on
+them.
+Despite Chancellor Sinsheimer's desire to keep the sea lion as the
+UCSC mascot, students voted 95% for the banana slug.
+There are just two complete mollusc genomes, [California sea hare and
+giant owl limpet], and neither are very complete.
+Banana slugs habitat is very diverse.  Though often found in conifer
+forests and considered an animal of the Northwest (first found in
+Washington or Oregon), they've been found in drier habitats: San
+Diego, Napa's McLaughlin Reserve (by small springs), abandoned rice
+patties in the Sacramento River Delta, oceanside iceplants in Pacific
+Grove.  High variation in the numbers you'll see on any day/site: none
+or dozens.
+They eat feces, hemlock, poison oak, mushrooms (reported but
+John has not seen), sorrel, ferns, ice plants, humus soil.  In the lab
+they eat hamburger, cat food, apples, beans, zucchini, mushrooms,
+yams, lettuce and milk.
+Colors may camouflage them, //e.g.// dead leaves often turn bright
+yellow, the color of species in Santa Cruz and the SF Bay area.  In
+other areas you'll find spotted slugs -- but they may be a different
+species.
+There predators may include [seemed uncertain] garter snakes,
+salamanders and newts, birds and some small mammals.  It is possible
+that some specific carnivorous snails and slugs eat banana slugs.
+//Aphallarion buttoni// originally thought to be a different species
+because no penes were found when dissected (late 19th century).
+However, a Stanford professor later found some with penes and so sent
+students into the field to study.  They observed apophallation.  That
+was the end of //buttoni// as a separate taxon.  It became //Ariolimax
+columbianus.//
+All banana slugs have an opening on the right side of the "head" for
+defecation, breathing, and copulation. The only way to distinguish
+species is by dissection of the genitalia.  [See slide *//Ariolimax
+Arilimax columbians// genitalia* for overview of genitalia.]  The
+gonad has a mix of testes and ovaries, and they can play both roles at
+same time curing copulation.  How is sperm kept separate during
+copulation?  It is not necessarily.  They can fertilize themselves.
+And aphalon are born without a penis [sometimes?].
+//Ariolimax Meadarion californicus// is found in San Mateo county.
+Santa Cruz has //dolichophallus//.  [See slide comparing their
+genitalia.]  Mead thoought //dolichophallus// and //californicus//
+were sufficiently different to be a separate species.
+A collaborator in Belgium has been sequencing banana slug
+mitochrondrial DNA.  They see at least five clades but cannot yet
+connect them.  ~"Morphologically distinct and molecularly distinct are
+not the same thing."  [See slide.]
+Interestingly the distribution of the salamander genus //Ensatia// is
+similar to that of banana slug [//dolichophallus//? -- see slide].  Is
+this a remnant of five million years ago when there were islands in
+the Monterey Bay?  Morphologically distinct but molecularly
+[mito. DNA] indistict suggests recent change.
+===== Janet Leonard talk =====
+Janet's interest is in sex selection.  Eberhard's hypothesis: [That we
+can ] classif[y] based on genitalia (as done with insects, spiders,
+//etc.//) suggests the importance of sex selection.  Genitalia
+differences in nearby counties are not explicable by natural
+selection, //e.g.// how would NS explain [improved fitness by a
+different vaginal muscle in the same geographical area.]
+The talk focused on courtship behavior:  much effort/expense in banana slug mating.
+//Ariolimax stramineus// courtship: antiparallel alignment of slugs is
+standard.  They line up right sides of their heads until the alignment
+allows copulation.  The first copulation takes place in about twenty
+minutes with subsequent occuring over about two hours.  No apophallation in the
+one shown on film.
+Mating film for //brachyphallus//: This is one of the three under
+//Ariolimax Meadarian//.  Note the initial biting and head swinging
+which seem to cause no damage.  The biting helps line up the head
+regions.  Banana slugs cannot reverse so the cirlcing helps get them
+get into position for mating.
+Mating film for //californicus//: Unilateral copulation (after two hours
+biting, head swinging).  It is hard to tell which plays the role of
+male and female but Janet thinks they alternate over a copulation
+session.
+Mating film for //dolicophallus//: Example of apophallation (by the
+first to withdraw).  How costly is this for a hermaphrodite?  It is
+pretty rare: 5 out of 100 copulations end in apophallation.
+Why does apophallation occur and when?  They have observed it only nine
+times and never by virgins.  Is it done as retaliation if one partner does not give
+any sperm?  Do they run out, and perhaps later in life focus on egg laying?
+Note in the table comparing copulations that //dolicophallus// and
+//californicus// are indistinguishable by mitochondrial DNA.
+The rapid morphological changes are among the evidence for sex
+selection, as well as the high cost of courtship/mating.  There is
+some evidence for sperm competition.
+Soon we should have based on microsatellite data (nuclear DNA) ...
+It is unknown how many chromosomes they have, though chromosome
+variation is usually not seen till "quite high" taxonomic levels.
+Their egg laying habits in the field are uncertain.  Perhaps under
+leaflitter.  They do not dig holes in moist soil like garden
+snails. In the lab at 19^C, they take seven weeks to hatch,
+sometimes two to three weeks longer.  The record for a clutch is
+seventy-five eggs (but this could have been multiple clutches since
+they don't check every day).  Egg size varies.  //Dollicophallus//
+eggs are almost the size of jellybelly and weigh up to half a gram.
+For //californicus// they're usually under 0.3g.
+Egg laying starts in fall and copulation is associated with foggy
+nights (late summer, Santa Cruz).  Eggs are laid October through
+December when the rains come and usually finished by February.
+Hypothesis: Low pressure systems trigger egg laying.  (This is based
+on lab observations, and makes sense since dehydration is the highest
+mortality source.  You want to lay eggs at the start of the rainy season
+in a moist place.)
+They have observed copulation for slugs as young as six months and egg
+laying as young as ten.
+How long do they live?  No one knows but perhaps two to three years.
+Some have lived thirty months in the lab (when sacrificed).

Banana Slug Genomics

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