Sunday, April 13, 2014

Ask An Expert: Hybrid Introgression and BC Butterflies

Biodiversity and genetic diversity are influenced by many factors...


What is hybrid introgression and does it occur in butterflies?

Answer (by Cris Guppy)

Hybrid introgression is the introduction of genes from the gene pool of one species into that of another, when the two species interbreed and produce offspring (hybridization) that are fertile, and the hybrid offspring continue to interbreed with one of the species.  An interesting case of hybrid introgression is the Propertius Duskywing butterfly (Erynnis propertius).  The overall range is the west coast of North America from San Diego north to central Vancouver Island, and DNA testing has found that the DNA is reasonably similar over that entire range (except for some subspecies-level variation).  However, populations from southern Vancouver Island and Puget Sound have two gene structures with about a 5% difference -- which is usually a large enough difference to indicate that two species are present. One gene structure matches the rest of the Propertius Duskywing and one matches Horace's Duskywing (E. horatius) of eastern North America.  At some undetermined time in the past, the range of the two species touched in the Puget Sound area, and they hybridized without merging into one species. The  range of Horace's Duskywing then retreated to east of the Rockies, but left behind some of its genetic material in the Propertius Duskywing gene pool.  The wing patterns and genitalia structure of the Propertius Duskywing all look the same, so the past hybridization is only detectable through DNA analysis. Quite cool!

Visit the E-Fauna BC atlas pages to learn about BC butterflies.
Read the E-Fauna BC Introduction to the Butterflies by Cris Guppy. 

Cris Guppy is a wildlife biologist and butterfly researcher based in the Yukon. He is co-author (with Jon Shepard) of Butterflies of British Columbia and is the butterfly advisor and butterfly photo reviewer on E-Fauna BC.  

Saturday, April 12, 2014

Ask An Expert: Tidal Pools


I was on the rocky shore to the west of Kits beach (down the steps at the end of Trutch Street) and I noticed that there is very little life in the tide pools other than algae and mussels. I didn't see any snails or hermit crabs at all. Is this natural for this area or have the snails, hermit crabs and other littoral zone life been killed by pollution?

Thank you,

Answer (by Tom Carefoot)

The beach in question is part of a sandstone outcropping that extends from the Alma Street area eastwards.  It is characterised by shallow depressions with loose rocks (and other "moveable objects").  There is nothing wrong with the water quality in the area, and further east the shore becomes quite rich with intertidal flora and fauna.  Still, with rocks and sediments moving in the waves, there is little chance of anything delicate surviving on the Trutch-street beach, and hermit crabs and crabs in general would also not like the shifting substratum.  As you note, shells would likely be a resource in short supply for any would-be hermit-crab colonisers.  You may have noticed at least a few winkles Littorina spp. higher up on the shore, but the larger dogwhelks Nucella lamellosa, whose shells would be of a more suitable habitable size than those of winkles, are absent from most Vancouver shores.  They used to be extremely common in the Harbour side of Stanley Park, but tributyltin present in the water likely killed them off.  You may know that this latter, a component of older anti-fouling paints, and quite effective in preventing barnacles and such from settling, is now banned from inshore waters of most countries in the world.  Its problem, discovered only in the 1980s, was that it created a condition in whelks known as imposex.  This refers to the masculinisation of females, or imposition of maleness in the females leading, within a few generations, to total sterilisation of a population.  I haven't been down to the Park to check on them for several years, so a visit to the beach near the HMCS Discovery site might be something useful to do.  The winkles mentioned above comprise two common species Littorina scutulata and L. sitkana.  These are high-intertidal dwelling herbivorous species, sometimes even supratidal, and are too small to eat (winkle-"picking" is a respectable profession on Atlantic shores and in Europe).  However, thanks probably to release by winkle-eaters who can purchase live east-coast Littorina littorea from several seafood-supply stores in Vancouver, this much larger and quite tasty species can now be found on some local Vancouver beaches.   It lives in the intertidal zone, much lower than the indigenous species just mentioned, and (should you be wondering) is unlikely to enter into direct competition with them.  Well, you probably have much more information here than you really wanted, but it's easy to ramble on about topics dealing with marine invertebrates.

If you have the inclination, you can get more information on imposex on A Snails Odyssey website.

Also, you can read more about littorines & relatives on A Snail's Odyssey. The information presented there mainly relates to information published by Dr. Chris Harley of the University of British Columbia who, along with his students, first noticed the presence of L. littorea on local beaches.

Tom Carefoot is Professor Emeritus, Department of Zoology, University of British Columbia and is also the author of A Snail's Odyssey, a comprehensive, research-based site dedicated to marine invertebrates.  Tom is a frequent contributor to E-Fauna BC.  

Atlas News: Our Maps

The maps on E-Flora and E-Fauna bc will be unavailable for a few days while the software licenses are updated.  They should be available early next week.

Friday, April 4, 2014

Half a Million Visits a Year: Our Regional Atlases Reach an International Audience

The numbers are now in! Our regional atlases of BC's flora and fauna--E-Flora BC and E-Fauna BC--are now drawing more than half a million visits a year!  Most of our visitors are from Canada, and the US, but there are many other countries represented. Many visitors are accessing the home page and searching for species information from there (~300,000) but a large number go directly to a species atlas page (400,000).   Based on the comments and inquiries we receive, our users include researchers, schools/students, government, conservation groups, and the general public.

The most popular group in the atlases?  Spiders!  The interest in spiders is high and everyone wants to know about Brown Recluse spiders (not found in BC), Black Widow Spiders and the Giant House Spider.  But, based on feedback, visitors are also keen on freshwater crustaceans, big furry wildlife (bears, wolves and cougars), and marine invertebrates (shorelines and tidal pool creataures).  In the plant world, listed species and invasive species are the big attractors. The photo galleries on both sites are heavily used by visitors aiming to identify what they've found.

Our blog is drawing a lot of interest, too, with up to 3000 visitors per month.  The most popular blog posts are, of course, spiders.  Robb Bennett's insights into our BC spiders are always a hit, but Tom Carefoot's blog posts on 'things marine' attract lots of visitors too. There is also a lot of interest in Ian Gardiner's finds in freshwater lakes in BC: the fairy shrimp, brine shrimp and water fleas. 

Interesting Facts:

The highest number of visitors to our blog in one day?  3897.

Most commonly used browser?  Firefox, followed by Chrome. The use of mobile devices and associated browsers is growing and now representing 10% of our visitors consistently.

Most frequently used search word?  Spiders and Brown Recluse Spiders.

Top Ten Countries Accessing the sites, in descending order: Canada, US, Russia, Ukraine, Germany, France, Latvia, UK, Poland.

Operating systems used, in descending order: Windows (59%), Macintosh (15%), iPhone (10%), iPad (4%), iPod (1%).