

189
DENVER MUSEUM OF NATURE & SCIENCE
REPORTS
|
No. 3, July 2, 2016
Student - oral presentation
Urban Islands: a biodiversity survey of
spiders on Portland, Oregon green roofs
Jessica Szabo, Susan Masta, Olyssa Starry
Portland State University Department of Biology PO
Box 751 Portland, Oregon 97207-0751, USA
szab@pdx.ed uUrban development reduces green space and causes
fragmentation of natural habitats, reducing the con-
nectivity of populations of organisms. Green roofs
(rooftops with vegetation and shallow soil) may help to
augment green space in cities and provide connectivity
for plant and animal populations. Spiders are good
bioindicators of the health of an ecosystem; if spiders
are abundant in green roof communities, there is a
food source (typically arthropods) available to them,
signaling a thriving ecosystem. We surveyed the spider
community on 8 green roofs in Portland, Oregon, sam-
pling every two weeks from April through September
over two years. We examined whether plant composi-
tion on the green roofs influenced spider biodiversity
and abundance by comparing herbaceous and
Sedum
planted roofs. We found that herbaceous roofs had only
slightly higher abundance and diversity of spiders, but
that both types of roofs harbored different compositions
of spider species. The most abundant families found
overall were Linyphiidae, Thomisidae, Salticidae and
Gnaphosidae. Spiders in the family Linyphiidae are
known to balloon as adults, which may explain why
they are the most abundant family on every roof. Bal-
looning allows for greater dispersal and thus, greater
access to high places like tall buildings. Interestingly,
the green roof watering regime did not affect spider
biodiversity, as the unwatered herbaceous roof had
equivalent spider diversity to the watered roof. We
suggest that cities incorporate a diversity of green roofs,
including those with herbaceous and
Sedum
plant-
ings, and low to no additional water, to best maintain
arthropod biodiversity.
Keywords: ecoroof, urban ecology, spider ecology, pitfall
trap
Student - poster presentation
Last male paternity bias in
Tetragnatha
–
does intermating interval matter?
Kaitlyn Dodson Tatro, Autumn Alexis Richardson, Anne
Danielson-Francois
University of Michigan - Dearborn, Department of
Natural Sciences, 4901 Evergreen Road, Dearborn,
Michigan 48128, USA
ketatro@umich.eduLong jawed spiders of the genus
Tetragnatha
have been
studied for their mating behavior, but few studies have
determined the paternity patterns found in these species.
Female reproductive morphology predicts that the last
male to mate should be favored in species with cul-de-sac
spermathecae, although other researchers have found either
extreme variability or a last-male bias for the first egg sacs
with an antichronological sequence of paternity for subse-
quent egg sacs. It has recently been demonstrated that males
can remove amorphous mating plugs composed of rival
male sperm. However, the influence of the age of the sperm
plug on the ability of males to remove it has not been tested.
Here, we used the classic sterile male technique to determine
whether or not paternity was influenced by the age of the
sperm plug in
Tetragnatha elongata
. Females were mated to
two males sequentially and assigned randomly to one of two
groups: presentation of the second male after either short
(15 min) or long (6 hour) intermating intervals. Across both
groups, we found a strong bias for last-male paternity in
the first egg sacs laid. Here, we report the paternity patterns
observed for subsequent egg sacs and the influence of the
intermating interval. We discuss the implications of our
findings for sperm competition in this species.
Keywords: sexual selection, sperm competition, sexual
behavior, paternity analysis
Oral presentation
Prey color biases, learning, and colorful
courtship in jumping spiders
Lisa Taylor
1
, Collette Cook
1
, Michelle Brock
1
, Michael
Vickers
1
, Nathan I. Morehouse
2
, Jeff Coco
1
, Lauren Gawell
1
,
Lauren Holian
1
1
Entomology and Nematology Department, University
20
th
International Congress of Arachnology