ecolonaught

Chronicles of a 21st century naturalist.


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Takahe Valley

My most recent field expedition was to Takahe Valley; a place with an interesting conservation narrative, beautiful scenery, and a fantastic place to do research.

I went to Takahe Valley March 7th – March 10th with along with two Landcare colleagues and another PhD student. Our purpose was to assist with end of the summer field data collection.

The  crew grabbing lunch.

The crew grabbing lunch.

Those of you well versed in your New Zealand native birds will recognize the name takahe (Porphyrio hochstetteri). The species was thought extinct when the last 4 known individuals were captured and killed in 1898. However, Geoffrey Orbell rediscovered a remnant population of the birds in a place isolated from human activities near Lake Te Anu (Takahe Valley) in 1948. Concerted conservation efforts since rediscovery have resulted in relatively successful recovery. The Fiordland National Park was created to ensure them a safe home, and deer control is carried out within the park to reduce competition for food. The wild population estimate as of 2013 is 263.

takahe

A takahe in captivity. Phtoto by New Zealand Department of Conservation (http://blog.doc.govt.nz/2014/12/01/takahe-finds-love-te-anau/)

I wasn’t able to see any of these beautiful birds (locally “blue chickens”), but I was able to see signs of their presence including well traveled tracks, digestive remains, freshly munched tussock grass, and tracks. Hopefully next time I will be able to sneak a peak!

I was able to see some other charismatic birds though including a Kea (Nestor notabilis), NZ rock wren (Xenicus gilviventris), rifleman (Acanthisitta chloris), and tomtit (Petroica macrocephala).

A Kea investigating our campsite, as well as me, to see if it can get an easy feed.

A Kea investigating our campsite, as well as me, to see if it can get an free feed.

The Fiordland foothills are composed of gneiss (metamorphosed from mostly granite and diorite). Apparently this is some of the oldest rock in NZ, originating from the Ordovocian period. The valleys and basins were etched through glacial erosion during the last ice age. Alpine areas have exposed rock or scree substrate, while basins soil is composed of podzolised gley and organic soils. The vegetation in our valley ranged from sub-alpine herbs up on the exposed rock and scree at the valley ridges to wetland species down in the basin. Beech forests and tussock grasses can be seen covering and deferentially partitioning large swaths of the valley.

The basin has a river flowing through it. This area is dominated by wetland vegetation.

The basin has a river flowing through it. This area is dominated by wetland vegetation.

Tussock grass vegetation dominates portions of the basin, as well as some portions of the lower and upper walls, of the valley. Forest dominates most of the midsection.

Tussock grass vegetation dominates portions of the basin, as well as some portions of the lower and upper walls, of the valley. Forest dominates most of the midsection.

campsite

We camped partially up the valley, at the head wall. This area has some tussocks but also some sub-alpine herbs due to the higher elevation and some wetland plants from the the head water flow.

valley ridge

The head wall ridge. This area has exposed rock and screes, mostly dominated by sub-alpine plants with some small tussocks.

The main purpose of our trip was research. There are transects of tussock grasses here that have been measured for over a decade, investigation the masting events of the tussocks (Chionochloa sp.). Masting is the phenomena of some plants to usually not produce many flowers/seeds most years, but every few years they will all create massive amounts of flowers/seeds. In North America most oak trees (Quercus sp.) display some level of masting.

A feather’s fate; only to drift on the low breeze; never to fly again

Another component of the research is to investigate the interacting influences of anticipated climate change, increasing soil N, and increasing soil C on tussock growth as well as reproduction. Climate change is simulated by putting translucent plastic around the bases of the tussock (creating a mini green house gas effect). Soil N is increased by adding fertilizer. Soil C is increased by sprinkling sugar on the plots. We had to count the number of tillers (stems) on every experimental plant (counts ranged from ~30 to ~800). The cages are to protect the tussocks from takahe, as this is their favorite food.

These are the experimental plots on the red tussock (C. rubra).

These are the experimental plots on the red tussock (C. rubra).

We also collected invertebrate data for each plot to see if the treatments (temperature * N * C) had an influence on invertebrate diversity or community composition.

Me emptying invertebrates from pitfall traps. These traps passively capture insects by trapping them in a cup filled with death liquid.

It was a fantastic trip filled with good company, good weather and goo food. I eagerly await my next expedition into Takahe Valley!

-Greg

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NZ Ecology Society Conference

My birthday was last week, and I had a great time! Although I don’t really have any insightful statements, I do have a lot of ecology to talk about. I celebrated by attending this year’s Ecology Conference at Massey University in Palmerston North. I was able to learn a great deal about New Zealand ecology by sitting in on some great talks as well as speaking with some inspiring scientists. I will be summarizing the highlights here.

I’ve always been fascinated by the trade-offs between sexual and asexual reproduction. Sexuality reaps the benefit of genetic diversity, but is a density dependent interaction (you need to be able to find a mate).  Being able to do a direct comparison is difficult because species usually can’t do both – but some do! Like the NZ snail. It reproduces sexually in a diploid state, but is able to switch to diploid (3 or 4 sets of chromosomes) as subsequently reproduces asexually. Laboratory experiments demonstrated the the asexual snails outperform sexual snails in every fitness metric (growth rate, strength, reproduction time, and reproductive output), but are only found in watersheds that are high in nutrients. This suggests that polyploidy is a competitive advantage if there are enough resources for extra sets of chromosomes but is unable to persist in low nutrient conditions, driving asexual populations locally extinct. Mechanisms related to how this with is made remain, but it is certainly a line of research worth continuing.

One research lab investigated the flammability of different types of plants by putting them in a grill! (with standardized procedures)

Through analysis of a wealth of extraordinarily preserved fossils and amber specimens it has been shown that although New Zealand’s contemporary insect communities are quite disparate, in the past a wealth of invertebrate diversity existed on the islands. These specimens date to before the last ice age, and so it is likely that changing climates and range reductions drove many of them extinct.

In an amazing demonstration of stabilizing selection pressure, it was demonstrated that a serious NZ invasive weed, gorse, has evolved larger seeds outside of its home range. In Europe it is paracitized by a beetle larvae, which feasts upon its seeds when young. It prefers larger seeds because they contain more food, thus when the beetle is present it exerts a pressure for smaller seed size. When the beetle is removed from the equation when gorse is transported to new territory that pressure is removed, seed sizes become larger over a few generations as larger seeds mean greater survivability in general. Neat!

I can’t wait to be presenting my own exciting findings next year!

 


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The program

The reason I ultimately decided to make the trip to New Zealand was the specific research program I applied for. I find this work fascinating, and hope that you will too.

I am enrolled in a 3 year PhD program with Dr. Steve Higgins at the University in Otago and Dr. William Lee with Landcare Research. Steve and my program are housed in the Botany department, although his research focuses on ecological modeling. Bill is an experimental and theoretical ecologist, and Landcare is a national government agency that  works on conservation biology issues.

My research focuses on evolutionary ecology, or using evolutionary theory to explain ecological phenomena. The study of ecology has two questions at its core: (1) why are there so many species? (2) why do species occur where/when they do, and how? Ultimately ecology seeks to gain insights to the underlying mechanisms of patterns we observe in nature. I will implement theory, experiments, and models to address these questions in an evolutionary context.

Although global diversity is great, it is not evenly distributed. Some groups have diversified greatly, while others have remained sparse. Furthermore, some lineages that are poorly diversified in mainland systems are highly so in nearby islands. Such is the case in New Zealand, and the primary question of my research. We hypothesize that groups of plants that colonized earlier geologically will have greater diversification due to radial divergence and niche preemption, or when they arrived they were able to take advantage of many novel habitats and speciate to utilize them. Later arriving species then are forced to fit into these communities, and are unable to diversify into new niches because they are already occupied. Earlier colonizers should also have competitive advantages, which would make them dominant and most abundant in community types.

Genetic data with phylogenetic modeling techniques will be implemented to construct evolutionary trees, as well as estimate colonization time. Experiments will be used to quantify competitive ability within and between lineages. After these data have been collected patterns of diversification will be modeled.

Hopefully you agree with me that understanding the underlying mechanisms speciation are interesting. I’ll provide updates as research progress is made.