Investigating a Range Expansion Associated with Anthropogenic Alterations in Cope’s Gray Treefrog (Hyla chrysoscelis) Utilizing Prey Selection Parameters
Miguel Avila Garcia
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08/03/2020
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The distribution of Cope's gray tree frog is speculated to have extended west from its original eastern range in Nebraska due to changes in precipitation events associated with climate change, habitat modifications accompanying agriculture, and fire suppression. The aim of this study was to determine a relationship between prey selection and range location by utilizing geographic and diet data.
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- [00:00:01.643]Hi my name is Miguel Avila Garcia & I am
- [00:00:04.053]senior Fisheries and Wildlife major. I
- [00:00:06.063]conducted my research under the guidance
- [00:00:08.293]of Dennis Ferraro of the School of Natural
- [00:00:10.753]Resources and I will be presenting
- [00:00:12.923]Investigating a Range Expansion Associated
- [00:00:14.926]with Anthropogenic Alterations in Cope's
- [00:00:17.463]Gray Treefrog Utilizing Prey Selection
- [00:00:19.743]Parameters. To begin with some background
- [00:00:22.333]information, amphibians are among the most
- [00:00:24.863]vulnerable vertebrates to the impacts of
- [00:00:27.253]climate change due to their morphological
- [00:00:29.763]and physiological traits. Habitat loss and
- [00:00:32.003]alteration along with fire suppression are
- [00:00:34.483]also the most serious threats to
- [00:00:36.553]amphibians. Additionally, some of the
- [00:00:38.883]consequences of climate change on
- [00:00:41.063]amphibians include changes in breeding
- [00:00:43.373]phenology, population declines, decreased
- [00:00:45.880]immune function, range shifts including
- [00:00:48.282]expansions and contractions,
- [00:00:50.163]morphological changes, and changes in
- [00:00:52.561]food availability. The study species in my
- [00:00:54.999]research was the Cope's gray treefrog or
- [00:00:57.441]Hyla chrysoscelis and in figure 1 you can
- [00:00:59.640]see an image of Cope's gray treefrog. They
- [00:01:01.888]are an arboreal, insectivorous, and
- [00:01:03.830]nocturnal anuran. They occur in riparian
- [00:01:05.967]woodlands in the Eastern U.S. and
- [00:01:08.052]recently the distribution in Nebraska
- [00:01:10.157]has expanded west from its original range
- [00:01:12.421]I hypothesize that Hyla chrysoscelis has
- [00:01:14.889]extended from its native range because of
- [00:01:17.559]climate change and other human activities
- [00:01:20.119]and this has initiated changes to their
- [00:01:22.252]diet. Some reasons why my research is
- [00:01:24.565]important is even though the
- [00:01:26.375]conservation status of Hyla
- [00:01:28.132]chrysoscelis is of least concern, it is
- [00:01:30.316]still important to study common species
- [00:01:32.585]because of the important niches they
- [00:01:34.870]serve in their ecosystems. Also, this
- [00:01:36.975]study could provide insight into their
- [00:01:39.212]ecology and the ecology of other similar
- [00:01:41.642]species. I collected data at Pioneers Park
- [00:01:43.975]Nature Center, Wagon Tongue Creek Preserve
- [00:01:46.111]and Crane Trust Nature and Visitor's
- [00:01:48.325]Center. In figure 5 you can see the
- [00:01:50.489]locations of my study sites in relation to
- [00:01:52.867]Nebraska. I aimed for a sample size of 60
- [00:01:55.466]frogs and the capturing methods I utilized
- [00:02:00.709]were by hand at Pioneers Park Nature
- [00:02:02.978]Center during nightly visits to breeding
- [00:02:05.380]choruses and with the use of PVC pipe
- [00:02:07.714]refugia during the daylight hours at
- [00:02:09.873]Pioneers Park Nature Center, Wagon Tongue
- [00:02:12.424]Creek Preserve, and Crane Trust Nature and
- [00:02:14.483]Visitor's Center. In figure 2 you can see
- [00:02:16.553]a photo of the PVC pipe refugia I utilized
- [00:02:18.613]in my study. Some more of the procedures
- [00:02:22.343]and analysis in my study were the stomach
- [00:02:25.831]contents of each treefrog was flushed
- [00:02:27.670]following a stomach flushing technique
- [00:02:29.496]which was gentle and humane for the frogs.
- [00:02:31.882]The specimens were held for 48 hours and
- [00:02:34.328]any fecal samples produced were collected.
- [00:02:36.804]The extracted stomach contents were then
- [00:02:39.303]analyzed for insect species and richness
- [00:02:41.403]as well as any fecal samples. I would then
- [00:02:43.678]go on to use ANOVA to determine the
- [00:02:45.937]relationship between prey selection and
- [00:02:48.242]range location. In figures 3 and 4 you can
- [00:02:52.050]see the stomach flushing technique. In
- [00:02:55.214]figure 3 you can see a plastic spatula
- [00:02:57.289]being used to open the mouth of Hyla
- [00:02:59.368]chrysoscelis and in figure 4 you can see
- [00:03:01.476]the metal catheter inserted into their
- [00:03:03.558]stomach which was then used to inject
- [00:03:05.693]water flushing out any stomach contents.
- [00:03:08.193]In figures 6 and 7 you can see photos of
- [00:03:11.883]the fecal matter under a microscope. As of
- [00:03:16.165]now I have captured 14 Hyla chrysoscelis
- [00:03:18.562]between Pioneers Park Nature Center and
- [00:03:21.182]Wagon Tongue Creek Preserve and data
- [00:03:23.364]collection is ongoing. The stomach
- [00:03:25.578]flushing technique did not produce any
- [00:03:27.857]stomach contents and contrary to a
- [00:03:29.901]study by Mahan and Johnson (2007) of
- [00:03:33.004]Hyla versicolor, a morphologically similar
- [00:03:35.305]species, it was determined that Hyla
- [00:03:37.444]chrysoscelis feeding was nocturnal.
- [00:03:40.459]Difficulty in producing stomach contents
- [00:03:42.511]has also been cited in other frog species.
- [00:03:44.734]And fecal samples were collected but need
- [00:03:46.709]to be analyzed for insects species and
- [00:03:48.559]richness. In the future I would like to
- [00:03:50.473]increase the sample size to produce a more
- [00:03:52.790]robust data set. And also I would like to
- [00:03:54.817]collect data at Crane Trust Nature and
- [00:03:56.681]Visitor's Center with an increased number
- [00:03:58.741]of PVC pipe refugia. Also, I would like to
- [00:04:00.785]collect specimens earlier in the day to
- [00:04:02.721]improve stomach flushing success since
- [00:04:05.043]they are nocturnal feeders and it's
- [00:04:06.765]thought that digestion occurs 1-2 hours
- [00:04:08.695]after feeding. I would also then analyze
- [00:04:12.007]the fecal matter. I would like to
- [00:04:14.584]acknowledge Professor Dennis Ferraro
- [00:04:16.796]who served as my faculty mentor over the
- [00:04:18.712]summer research project. Also Lincoln
- [00:04:20.532]Parks and Recreation for allowing me to
- [00:04:22.580]collect data at Pioneers Park Nature
- [00:04:24.372]Center. Ron and Judy Parks who allowed me
- [00:04:26.744]to collect data at Wagon Tongue Creek
- [00:04:31.060]Preserve and Emma Chelsey, a UCARE student
- [00:04:33.161]who helped me to collect data at Wagon
- [00:04:35.401]Tongue Creek Preserve and finally the UNL
- [00:04:37.964]McNair Scholars Program. Thank you!
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