Seed dispersal systems in the New Zealand flora

Evolutionary Ecology, 2011

A range of distinctive dispersal features have been recognised within the New Zealand flora, and a wide range of fauna are involved in the dispersal of seed in New Zealand, either by consuming fruit or seed, or as transporters of adhesive seed. In this study the composition of New Zealand's zoochorous fauna (except insects) was examined using both trait matching within environmental, morphological and behavioural variables, and compared to the trait pattern of the groups of plant species they disperse. The importance of the different dispersal groups to the plant species they disperse varies with habitat, landform, region of New Zealand, foraging behaviour, and morphology. Over half of New Zealand's vertebrate fauna are involved in fruit dispersal, though only 6% are considered frugivorous-the remainder include varying quantities of insects and other plant material in their diets. Flighted species are over-represented in wooded environments and higher strata and flightless species predominate in low alpine and grassland habitats. The frugivore-fruiting plant interaction group shows some indications of ecological generalism as frugivorous species consume a range of fruit sizes across all vegetation strata and fruit-bearing plants have lower species diversity and occupy a wide range of habitats. Granivores are over-represented in wetland habitats and the eastern South Island. The importance of species which unintentionally disperse adhesive seed depends on whether they are volant (higher importance in coastal environments) or flightless (higher importance dry grasslands and in low alpine areas). A subgroup of birds, such as the ratite Apteryx spp. and the now extinct Dinornithiform moa, with loose feathers (''velcro'' Electronic supplementary material The online version of this article (species) are over-represented in lower vegetation strata and this matches the zone where many attachment-dispersed plant species present their seed.

Trends in Ecology & …, 2002

Australian Journal of Botany, 2001

New Zealand is generally thought to have been physically isolated from the rest of the world for over 60million years. But physical isolation may not mean biotic isolation, at least on the time scale of millions of years. Are New Zealand’s present complement of plants the direct descendants of what originally rafted from Gondwana?Or has there been total extinction of this initial flora with replacement through long-distance dispersal (a complete biotic turnover)? These are two possible extremes which have come under recent discussion. Can the fossil record be used to decide the relative importance of the two endpoints, or is it simply too incomplete and too dependent onfactors of chance? This paper suggests two approaches to the problem — the use of statistics to apply levels of confidence to first appearances in the fossil record and the analysis of trends based on the entire palynorecord. Statistics can suggest that the first appearance of a taxon was after New Zealand broke away from Gondwana — as long as the first appearance in the record was not due to an increase in biomass from an initially rare state. Two observations can be drawn from the overall palynorecord that are independent of changes in biomass: (1)The first appearance of palynotaxa common to both Australia and New Zealand is decidedly non-random.Most taxa occur first in Australia. This suggests a bias in air or water transport from west to east. (2)The percentage of endemic palynospecies in New Zealand shows no simple correlation with the time NewZealand drifted into isolation.The conifer macrorecord also hints at complete turnover since the Cretaceous

The Journal of Ecology, 1994

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2012

ACKNOWLEDGMENTS 9 DECLARATION OF CONTRIBUTIONS 11 1 INTRODUCTION 13 1.1 The importance of seed dispersal and post-dispersal processes for plant recruitment 1.2 Seed dispersal and post-dispersal as spatially explicit processes 1.2.1 Seed dispersal 1.2.2 Post-dispersal 1.3 The present state of seed dispersal, seed and seedling predation in New Zealand 1.3.1 Seed dispersers 1.3.2 Post-dispersal seed predators and ground herbivores 1.4 Thesis outline 2 FRUGIVORES ENHANCE SMALL-SCALE DIVERSITY IN THE SEED RAIN OF A MATURE TEMPERATE FOREST 22 2.1 Abstract 2.2 Introduction 2.3 Methods 2.3.1 Study species and sites 2.3.2 Experimental plots 2.3.3 Statistical analyses 2.4 Results 2.4.1 Change in seed diversity 2.4.2 Spatial associations between seeds and trees 2.5 Discussion 2.5.1 Limitations of the study: seed types and masting 2.5.2 Possible outcomes of the increase in seed-fall diversity 2.5.3 Concluding remarks 3 BIOTIC SEED DISPERSAL DECREASES SEED RAIN HETEROGENEITY IN A MIXED TEMPERATE FOREST 41 3.1 Abstract 3.2 Introduction 3.3 Methods 3.3.1 Study site and species 3.3.2 Seed rain 3.3.3 Data analysis 3.4 Results 3.4.1 Seed removal rates 3.4.2 Species composition at canopy and seed rain levels 3.4.3 Effects of tree canopies on seed rain 3.5 Discussion 3.5.1 Seed rain 3.5.2 Community composition and homogenization of seed rain 3.5.3 Effects of tree canopies on seed rain 3.5.4 Concluding remarks 3

New Zealand Garden Journal, 2008

Journal of …, 2007

New Zealand Journal of Botany, 2004

We tested the relative frequency of pollen limitation and dispersal limitation for two birdpollinated and bird-dispersed New Zealand mistletoes, Peraxilla tetrapetala and Alepis flavida, at a South Island site where the bellbird (Anthornis melanura) is the sole pollinator and disperser. There was no evidence of dispersal limitation for P. tetrapetala over four seasons or A. flavida over two seasons. Few ripe fruits were present on plants at any one time (usually <5%), and more than 90% of the fruit crop was removed. A. flavida was not pollen limited, but P. tetrapetala was significantly pollen limited in 6 of 10 years. The presence of pollen limitation but not dispersal limitation, despite both services depending on the same bird, is influenced by the much faster rates of flower ripening per day compared with fruit ripening (15-54 times faster in P. tetrapetala). In New Zealand, pollination failure probably threatens at least as many plant species as dispersal failure. In theory, dispersal should threaten fewer plant species, because dispersal usually involves more animal species, makes smaller quantitative demands on the dispersers (fewer fruits ripening per day, and fruits can wait longer for attention), and may be less obligate for at least some reproduction to occur.

Diversity and Distributions, 2010

Aim A species’ dispersal characteristics will play a key role in determining its likely fate during a period of environmental change. However, these characteristics are not constant within a species – instead, there is often both considerable interpopulation and interindividual variability. Also changes in selection pressures can result in the evolution of dispersal characteristics, with knock-on consequences for a species’ population dynamics. Our aim here is to make our theoretical understanding of dispersal evolution more conservation-relevant by moving beyond the rather abstract, phenomenological models that have dominated the literature towards a more mechanism-based approach.Methods We introduce a continuous-space, individual-based model for wind-dispersed plants where release height is determined by an individual’s ‘genotype’. A mechanistic wind dispersal model is used to simulate seed dispersal. Selection acts on variation in release height that is generated through mutation.Results We confirm that, when habitat is fragmented, both evolutionary rescue and evolutionary suicide remain possible outcomes when a mechanistic dispersal model is used. We also demonstrate the potential for what we term evolutionary entrapment. A population that under some conditions can evolve to be sufficiently dispersive that it expands rapidly across a fragmented landscape can, under different conditions, become trapped by a combination of limited dispersal and a large gap between patches.Conclusions While developing evolutionary models to be used as conservation tools is undoubtedly a challenge, we believe that, with a concerted collaborative effort linking the knowledge and methods of ecologists, evolutionary biologists and geneticists, it is an achievable aim.