Wright et al. (2006): The road from Santa Rosalia: A faster tempo of evolution in tropical climates.

Wright, S. D., J. Keeling, and L. N. Gillman. 2006. The road from Santa Rosalia: A faster tempo of evolution in tropical climates. Proceedings of the National Academy of Sciences, USA 103:7718-7722.

This study has demonstrated for the first time that molecular evolution proceeds at a faster tempo in the tropics than at higher latitudes. Forty-five woody rainforest plant genera were identified that have species occurring in both tropical and temperate climates. Numerous New Zealand species were included, in part because New Zealand carries into high latitudes a large number of woody plant genera that also occur in lowland tropical rainforest assemblages. For each genus one species was selected from the highest latitude and altitude possible and another selected from the lowest latitude and altitude possible. The ITS region of rDNA was then sequenced and substitution rates for each species pair were compared using a confamiliar outgroup. The rate of molecular evolution in the tropical species was found to be, on average, twice that in temperate species. Probably the most fundamental ecological pattern in nature is the declining species richness with increasing distance from the equator. It is suggested that differential rates of molecular evolution might provide the mechanism responsible for this pattern.

Introducing New Zealand Ecology Reviews

A few years back Alastair Robertson (Massey University) had the excellent idea of using the newsletter and website of the NZ Ecological Society to highlight important papers on New Zealand ecology that are published internationally. The project became known as HotScience and it invited members of the NZ Ecological Society to submit citations and summaries of the NZ ecology in such publications. It worked well for a while but submissions to the newsletter have dwindled recently and the society's overcommitted volunteer webmaster (me) got behind on updating the HotScience area of the society webpages (www.nzes.org.nz).

I am reviving the project with a new format and new optimism, as a web log ("blog"). A blog has two great advantages over our earlier system. It greatly streamlines the process of posting entries by allowing members to post their own summaries and/or reviews of NZ ecological science directly to the blog. It also allows members and other interested people to comment on these entries. Feel free to publicly disagree with what is posted. This is science, after all. Anyone can view the website and I have it currently set so that anyone can comment on posted articles. I will keep an eye on the posts and comments and only step in as moderator if necessary.

Because of the blog's ability to discuss and criticise papers as well as summarise them, I have renamed the project New Zealand Ecology Reviews. (The name Hotscience has also been subsequently adopted by a New Zealand website, www.hotscience.co.nz, which provides science resource for teachers.)

If you want to post a review or summary of a new article to New Zealand Ecology Reviews, you will need to be a member of this blog. This is free and easy but needs to be approved by a blog administrator (currently just me but easily expanded to others who wish to share the responsibility). Please contact me at webmaster [at] nzes.org.nz to request blog membership. Membership of the blog is restricted to NZ Ecological Society members. You can join the society at www.nzes.org.nz/join.html for a modest annual subscription.

I have posted all previous HotScience entries into New Zealand Ecology Reviews. I don't have a record of who sent these in so these are posted anonymously. If you originally sent a HotScience summary into the society newsletter and would like to be acknowledged in New Zealand Ecology Reviews for having done so, please contact me and I can make you the author of the post.

Efford et al. (2005): A field test of two methods for density estimation.

Efford, M.G., Warburton, B., Coleman, M. C. and Barker R. J. 2005. A field test of two methods for density estimation. Wildlife Society Bulletin 33: 731–738.

Population density estimation with a new spatially explicit capture–recapture method was tested in the field and compared to distance analysis of data from trapping webs. Brushtail possums were trapped in pine forest at Waitarere, near Foxton. Capture–recapture with hollow trapping squares gave an estimate (1.9/ha) that was close to the result from nearly complete removal (2.3/ha). Trapping webs gave highly biased estimates (6.5–8.0/ha), consistent with Monte Carlo simulations. The spatially explicit capture–recapture method places few constraints on the spatial configuration of sampling; dispersed configurations (e.g. randomly sited trap clusters) may be used to estimate mean density across landscapes. See www.landcareresearch.co.nz/services/software/density for software and a pdf of the paper.

Urlich et al. (2005): Tree regeneration in a New Zealand rain forest influenced by disturbance and drainage interactions.

Urlich, S.C.; Stewart, G.H.; Duncan, R.P.; Almond, P.C. 2005. Tree regeneration in a New Zealand rain forest influenced by disturbance and drainage interactions. Journal of Vegetation Science 16: 423–432.

Question: Does canopy tree regeneration response to difference large disturbances vary with soil drainage?

Location: Old-growth conifer (Dacrydium and Dacrycarpus), angiosperm (Nothofagus and Weinmannia) rain forest, Mount Harata, South Island, New Zealand.

Methods: Trees were aged (1056 cores) to reconstruct stand history in 20 (0.12–0.2 ha) plots with different underlying drainage. Spatial analyses of an additional 805 tree ages collected from two (0.3–0.7 ha) plots were conducted to detect patchiness for five canopy tree species. Microsite preferences for trees and saplings were determined.

Results: There were clear differences in species regeneration patterns on soils with different drainage. Conifer recruitment occurred infrequently in even-aged patches (>1000 m2) and only on poorly drained soils. Periodic Nothofagus fusca and N. menziesii recruitment occurred more frequently in different sized canopy openings on all soils. Weinmannia recruitment was more continuous on all soils reflecting their greater relative shade-tolerance. Distinct periods of recruitment that occurred in the last 400 years matched known large disturbances in the region. These events affected species differently as soil drainage varied. Follow- ing earthquakes, both conifer and N. menziesii regenerated on poorly drained soils, while Nothofagus species and Weinmannia regenerated on well drained soils. However, Dacrydium failed to regenerate after patchy storm damage in the wetter forest interior; instead faster growing N. fusca captured elevated microsites caused by uprooting.

Conclusions: Underlying drainage influenced species composition, while variation in the impacts of large disturbance regulated relative species abundances on different soils.

Gillman and Ogden (2005): Microsite heterogeneity in litterfall risk to seedlings.

Gillman, L. N., and J. Ogden. 2005. Microsite heterogeneity in litterfall risk to seedlings. Austral Ecology 30:497–504.

Litterfall is an important cause of damage and mortality to seedlings in many forests. However, this study is the first to demonstrate variable risks of litterfall damage among different microsites. Artificial seedlings were ‘planted’ along transects in each of two New Zealand forests, and the overhead species recorded. The artificial seedlings were monitored monthly for damage over two years. The risk of damage differed significantly among microsites from 2% to 30% per y (P < 0.0005). Seedlings differ in resilience to litterfall (Gillman et al. 2003) and, therefore, microsites with different litterfall risks provide the potential for regeneration niche differentiation.

Willis and Millar (2005): Using marine reserves to estimate fishing mortality.

Willis, T.J. & R.B. Millar (2005) Using marine reserves to estimate fishing mortality. Ecology Letters 8: 47–52.

The pervasive effects of fishing mean that what is generally seen on our coasts is not ‘natural’. Here we demonstrate how no-take marine reserves, where all forms of human-induced disturbance are forbidden, can be used to estimate fishing mortality independently of the fishery. We suggest that reserves can be used to estimate other important population parameters in exploited marine species. Reserves can be used to combat the ‘shifting baseline’ syndrome and provide controls for determining what is natural in the oceans.

Efford and Cowan (2004): Long-term population trend of Trichosurus vulpecula in the Orongorongo Valley, New Zealand.

Efford, M. G.; Cowan, P. E. 2004. Long-term population trend of Trichosurus vulpecula in the Orongorongo Valley, New Zealand. In: R. L. Goldingay and S. M. Jackson (eds.) The biology of Australian possums and gliders. Surrey Beatty & Sons, Chipping Norton. Pp. 471–483.

Browsing by introduced brushtail possums has been predicted to shift the species composition of native forests away from palatable species, and thereby to reduce the density of possums those forests support. We tested this prediction with data from a population of possums monitored by capture–recapture over 35 years. Annual density varied within a relatively narrow band (6.5–13.7/ha) and the overall trend was slightly positive (+0.04 ± 0.025 /ha/year), despite the decline of some ‘preferred’ plant species. We speculate that possum carrying capacity was buffered against the loss of palatable plants because these were replaced by more resilient and fast-growing palatable species.

Joy and Death (2004): Predictive modelling and spatial mapping of freshwater fish and decapod assemblages.

Joy, M.K. & Death, R.G. (2004) Predictive modelling and spatial mapping of freshwater fish and decapod assemblages: an integrated GIS and neural network approach. Freshwater Biology, 49, 1036–1052.

We used stream fish and decapod spatial occurrence data extracted from the New Zealand Freshwater Fish Database combined with recent surveys and geospatial landuse data, geomorphologic, climatic, and spatial data in a geographical information system (GIS) to model fish occurrence in the Wellington Region, New Zealand. To predict the occurrence of each species at a site from a common set of predictor variables we used a multi- response, artificial neural network (ANN), to produce a single model to predict the entire fish and decapod assemblage in one procedure. The predictions from the ANN using this landscape scale data proved very accurate and four other evaluation metrics independent of species abundance or probability thresholds also confirmed the accuracy of the model. The geospatial data available for the entire regional river network were then used to create a habitat-suitability map for all 18 species over the regional river network using GIS. This prediction map has many potential uses including; monitoring and predicting temporal changes in fish communities caused by human activities and shifts in climate, identifying of areas in need of protection, biodiversity hotspots, and areas for the reintroduction of endangered or rare species.

Joy and Death (2004): Application of the Index of Biotic Integrity Methodology to New Zealand Freshwater Fish Communities.

Joy, M.K. & Death, R.G. (2004) Application of the Index of Biotic Integrity Methodology to New Zealand Freshwater Fish Communities. Environmental Management, 34, 415–428.

An index of biotic integrity (IBI) was developed for freshwater fish in New Zealand streams. Data on freshwater fish occurrence for 5007 sites over the entire country were obtained from the New Zealand freshwater fish database for the period 1980–2002. Corresponding environmental descriptors for the stream catchments above or at each of these sites were obtained from a number of databases using a geographic information system. Of the 12 original North American IBI metrics, only six were adapted and applied because of differences between the fish faunas of New Zealand and the United States of America. A number of evaluation methods showed all six metrics contributed to the overall IBI scores with high levels of consistency. The IBI assessment of sites sampled at different times showed high levels of temporal concordance. Overall, the results presented demonstrate the potential for New Zealand freshwater fish to be used to assess river condition at large spatial scales in New Zealand in the absence of specifically selected reference sites.

Russell and Clout (2004): Modelling the distribution and interaction of introduced rodents on New Zealand offshore islands.

Russell, J.C.; Clout, M.N. 2004. Modelling the distribution and interaction of introduced rodents on New Zealand offshore islands. Global Ecology and Biogeography 13: 497–507.

Invasion of New Zealand’s offshore islands by the four introduced rodents has caused widespread damage to the native biota. Here the geographical and ecological factors that relate to their distribution on offshore islands are examined, as are interactions between their distributions. The ship rat appears most widely distributed, and the most dominant, while kiore have suffered mostly from the expansion of ship rats and to a lesser extent Norway rats. The distribution of mice remains unexplained. Their coexistence is explained by differences in competitive ability and dispersal.