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lecture_notes:04-23-2010 [2010/04/28 09:58]
jmagasin
lecture_notes:04-23-2010 [2010/05/01 09:00] (current)
jlong Link to Slides of John and Jan
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 ====== Slides ====== ====== 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/​]] ​.\\
  
  
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 John originally worked with sea urchins and sea stars primarily. John originally worked with sea urchins and sea stars primarily.
-Janet joined the lab about twelve years ago to study marine slugs.\\+Janet joined the lab about twelve years ago to study marine slugs.
 She was interested in hermaphrodite mating behavior. ​ Banana slugs' She was interested in hermaphrodite mating behavior. ​ Banana slugs'
-rare behavior of apophallation became a research focus. ​ No one had\\+rare behavior of apophallation became a research focus. ​ No one had
 really studied banana slugs [academically] since the forties. ​ Alice really studied banana slugs [academically] since the forties. ​ Alice
-Bryant Harper (Aptos naturalist, works with Santa Cruz Museum of\\+Bryant Harper (Aptos naturalist, works with Santa Cruz Museum of
 Natural History) wrote __The Banana Slug__ (1988), the best book on Natural History) wrote __The Banana Slug__ (1988), the best book on
 them. them.
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 Banana slugs habitat is very diverse. ​ Though often found in conifer Banana slugs habitat is very diverse. ​ Though often found in conifer
-forests and considered an animal of the Northwest (first found in\\+forests and considered an animal of the Northwest (first found in
 Washington or Oregon), they'​ve been found in drier habitats: San Washington or Oregon), they'​ve been found in drier habitats: San
-Diego, Napa's McLaughlin Reserve (by small springs), abandoned rice\\+Diego, Napa's McLaughlin Reserve (by small springs), abandoned rice
 patties in the Sacramento River Delta, oceanside iceplants in Pacific patties in the Sacramento River Delta, oceanside iceplants in Pacific
-Grove. ​ High variation in the numbers you'll see on any day/site: none\\+Grove. ​ High variation in the numbers you'll see on any day/site: none
 or dozens. or dozens.
  
 They eat feces, hemlock, poison oak, mushrooms (reported but They eat feces, hemlock, poison oak, mushrooms (reported but
-John has not seen), sorrel, ferns, ice plants, humus soil.  In the lab\\+John has not seen), sorrel, ferns, ice plants, humus soil.  In the lab
 they eat hamburger, cat food, apples, beans, zucchini, mushrooms, they eat hamburger, cat food, apples, beans, zucchini, mushrooms,
 yams, lettuce and milk. yams, lettuce and milk.
  
 Colors may camouflage them, //e.g.// dead leaves often turn bright 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\\+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 other areas you'll find spotted slugs -- but they may be a different
 species. species.
  
 There predators may include [seemed uncertain] garter snakes, There predators may include [seemed uncertain] garter snakes,
-salamanders and newts, birds and some small mammals. ​ It is possible\\+salamanders and newts, birds and some small mammals. ​ It is possible
 that some specific carnivorous snails and slugs eat banana slugs. that some specific carnivorous snails and slugs eat banana slugs.
  
  
 //​Aphallarion buttoni// originally thought to be a different species //​Aphallarion buttoni// originally thought to be a different species
-because no penes were found when dissected (late 19th century).\\+because no penes were found when dissected (late 19th century).
 However, a Stanford professor later found some with penes and so sent However, a Stanford professor later found some with penes and so sent
-students into the field to study. ​ They observed apophallation. ​ That\\+students into the field to study. ​ They observed apophallation. ​ That
 was the end of //buttoni// as a separate taxon. ​ It became //Ariolimax was the end of //buttoni// as a separate taxon. ​ It became //Ariolimax
 columbianus.//​ columbianus.//​
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 All banana slugs have an opening on the right side of the "​head"​ for All banana slugs have an opening on the right side of the "​head"​ for
-defecation, breathing, and copulation. The only way to distinguish\\+defecation, breathing, and copulation. The only way to distinguish
 species is by dissection of the genitalia. ​ [See slide *//​Ariolimax species is by dissection of the genitalia. ​ [See slide *//​Ariolimax
-Arilimax columbians//​ genitalia* for overview of genitalia.] ​ The\\+Arilimax columbians//​ genitalia* for overview of genitalia.] ​ The
 gonad has a mix of testes and ovaries, and they can play both roles at 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\\+same time curing copulation. ​ How is sperm kept separate during
 copulation? ​ It is not necessarily. ​ They can fertilize themselves. copulation? ​ It is not necessarily. ​ They can fertilize themselves.
  
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 //Ariolimax Meadarion californicus//​ is found in San Mateo county. //Ariolimax Meadarion californicus//​ is found in San Mateo county.
-Santa Cruz has //​dolichophallus//​. ​ [See slide comparing their\\+Santa Cruz has //​dolichophallus//​. ​ [See slide comparing their
 genitalia.] ​ Mead thoought //​dolichophallus//​ and //​californicus//​ genitalia.] ​ Mead thoought //​dolichophallus//​ and //​californicus//​
 were sufficiently different to be a separate species. were sufficiently different to be a separate species.
  
 A collaborator in Belgium has been sequencing banana slug A collaborator in Belgium has been sequencing banana slug
-mitochrondrial DNA.  They see at least five clades but cannot yet\\+mitochrondrial DNA.  They see at least five clades but cannot yet
 connect them.  ~"​Morphologically distinct and molecularly distinct are connect them.  ~"​Morphologically distinct and molecularly distinct are
 not the same thing." ​ [See slide.] not the same thing." ​ [See slide.]
  
 Interestingly the distribution of the salamander genus //Ensatia// is Interestingly the distribution of the salamander genus //Ensatia// is
-similar to that of banana slug [//​dolichophallus//?​ -- see slide]. ​ Is\\+similar to that of banana slug [//​dolichophallus//?​ -- see slide]. ​ Is
 this a remnant of five million years ago when there were islands in this a remnant of five million years ago when there were islands in
-the Monterey Bay?  Morphologically distinct but molecularly\\+the Monterey Bay?  Morphologically distinct but molecularly
 [mito. DNA] indistict suggests recent change. [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).
lecture_notes/04-23-2010.1272473888.txt.gz ยท Last modified: 2010/04/28 09:58 by jmagasin