Conservation in the wild can serve humanity and allow speciation into the future, for those species not driven to extinction. Destruction and fragmentation of habitat could drive speciation by creating disjunct populations with no gene flow!
The importance of plants and biodiversity
Mankind uses plants for fibre, food, medicine, and environmental services, such as storing carbon and cleaning water systems. Plants protect against dry land salinity, and coastal inundation. Because humans continue to use plants for survival diversity may hold valuable genetic material as we enter rapid climate change. In antiquity, hydraulic civilisations in the Middle East, (irrigation 5,500 B.P., led to dry land salinity over 2-3,000 years), the Indian subcontinent and Northern Asia displaced native ecosystems. Australia is unique, as an island/continent because changes, to hydrology and natural communities, due to irrigation agriculture only commenced 230 years ago, with the arrival of Europeans.
Australia separated from Antarctica approximately 45 million years B.P. This geographic isolation has driven allopatric speciation. Accordingly, 92 % of Australian endemic plants are unique to Australia. Moreover, since European settlement 83 higher plant species have become extinct, while 6.8% of Australian vascular plants are currently in danger of extinction.
Challenges to conservation of endangered communities
So, why act now? We have reached a crossroads, and whether we do anything about it or not; our world is changing. One of the key challenges, at this time, is the conservation of endangered ecological communities. Coastal ecosystems are particularly under pressure by human development, containing a large proportion of endangered ecological communities. The Ocean Shores development is an example of the clearing of littoral rainforest for housing development. Clearing was so rapid and comprehensive that, for example, eight of nine Acronychia littoralis trees were bulldozed (Floyd Australian rainforests), before they had been described.
Inland communities are also under threat. Due to the fragile landscape the activities of pastoralists, and to a lesser extent indigenous peoples, have greatly impacted the landscape. Now, mining threatens inland spring-fed waterways. Doongmabulla Springs, nationally protected wetlands, contain grasses and sedges endemic only to these areas. Elsewhere in Queensland aquifer-fed springs have been heavily impacted by development. In native grasslands at Moray Downs, a population of the endangered black-throated finches, Poephila cincta, was recorded (2013) at Adani’s proposed mine-site in the Galilee basin.
Resilience in rainforest communities
The research of Rossetto from populations to communities (2008) indicates that while some Australian rainforest species have become extinct, others have survived in refugia, providing seed banks for future recolonisation. Rossetto found that species, similar to those of mid- Eocene, have persisted through long-term climate change, as well as through the rapid climate changes of the Pleistocene ice ages. The range of the rainforest communities has gone through periods of expansion and contraction. The most recent examples of the rapid recolonisation, 8,000 years ago, of rainforest species, has occurred in the Eastern Qld, NSW border areas and in the wet tropics.
Rossetto and Kooyman maintain that in rainforest communities there is a tension between dispersal and persistence as a survival mechanism. Dispersal refers to the ability of rainforest trees to spread their seed widely. In fragmented forests where there are few dispersal mechanisms for large-fruited trees, plants can persist mainly by vegetative reproduction. For example, Rosetto and Kooyman suggest, it is the lack of long range dispersal mechanisms, coupled with resprouting potential, which limit the spatial distribution of Eidothea hardeniana, Nightcap Oak. It may be limited by the ability of the dispersers, terrestrial mammals, to carry the large seeds long-distances to other suitable available niches, rather than a reduction of alleles as would be caused by genetic drift. However, genetic tests have shown that in this species, where there are more closely spaced individuals, there is less variation.
Multi-species recovery programs
Saving our species technical report (Department of Environment and Heritage, NSW 2013) identifies five priority levels for threatened species management. The third asks if there is sufficient knowledge of the species ecology, distribution and management requirements? This can identify data-deficient threatened species, requiring further research into life history, threats and distribution.
Meaningful patterns in evolutionary ecology recognise:
- biogeographical barriers driving allopatric speciation
- trait-based species groupings
- potential and realised niche modelling.
The most successful approach will combine these into the development and implementation of multi-species recovery plans. Functional trait-based flora groups may be used as a guide to model appropriate placement of plants whose life histories have not yet been studied, by comparing with species allocated to the same trait-based flora group.
What options for the future?
Human activity can assist speciation into the future by conserving ecological communities and by linking communities with stepping-stones; Coastal connectors, a system of public reserves connecting small wetlands, semi-cleared ridges and riparian strips. By selecting plants, using functional trait based flora groups, suites of species can be used to connect and extend the existing corridors. The successful project will identify geographical barriers and utilise existing niches, planting species from the appropriate flora group and biogeographic region.