RC #24 甲壳虫特点 原文

reallyfly

其實lttbelief 是對的,不過少了last paragraph 是有考題的


Why beetles are good palaeoclimatic and palaeoenvironmental proxies


Beetle fossils are commonly preserved as disarticulated skeletal fragments in organic sediments such as clays, peats, sands and silts. These fragments preserve well due to their robust nature and structural details can often be distinguished allowing the beetles to be identified to species level. In most cases identification has revealed fossilised beetles to be extant species which indicates a great degree of morphological constancy throughout the Quaternary (the last 1.64 million years). This constancy includes that of key characters, such as genitalia, used in the identification of taxa. As morphology does not appear to have evolved it is generally assumed that the physiological requirements of beetles have also remained constant.


Evidence to support this assumption also exists in the fact that the composition of beetle communities has, like morphology, remained relatively constant throughout the Quaternary and that host-specific phytophagous  species can be sometimes be found in association with the macrofossils of their host plant. Due to this observed constancy and the ectothermicnature of beetles – and thus reliance on environmental conditions – beetle fossils can therefore make excellent indicators of palaeoenvironment.


Fossil beetle analysis has a number of advantages over other biological proxies such as pollen. Beetles are the most diverse group of organisms filling a large range of ecological rolesand habitats from deserts to rainforests to the littoral zone. Beetles, and insects in general, respond rapidly to environmental change by dispersal, rather than undergoing speciation, and, as stated above, fossils are generally identifiable to species level. In contrast, New Zealand pollen studies suffer from the fact that some genera of plants contain species with different ecological requirements, but with indistinguishable pollen. Furthermore predatory and scavenging beetle species are able to take advantage of recently modified areas (along with pioneer plant species) before the trees and shrubs with similar climatic requirements. Trees and shrubs can therefore lag behind the actual period of climatic change and the resultant spread of beetles. This ability to rapidly respond to climatic change can revealed short-term climate fluctuations that are not observed in the pollen record . Beetles fossils also avoid the problem of contamination of the local pollen rain (and hence local climate signal) by long-distance wind dispersed pollen such as that of Nothofagus .


Like palynology, initial beetle studies were qualitative in nature. The development of the Mutual Climatic Range (MCR) by Atkinson et. al. (1987) as a method of quantifying palaeoclimate has further increased the usefulness of beetle fossils in reconstructing the past climate of the Quaternary. This quantitative method has enabled studies of beetle fossils to be compared to (eg. Elias, 1997), or combined with (eg. Guiot et. al., 1993), other proxy data to provide a more complete palaeoclimatic and palaeoenvironmental reconstruction.


MCR uses the modern distribution of a species found within a fossil beetle assemblage to construct a climate envelope for that species. This is based on the observation that the contemporary distribution of a beetle species is seen to measure its climatic tolerances. Only predators and scavengers are used to calculate MCR as the distribution of some herbivorous[食species may be limited by the range of a host plant  rather than by direct climatic influences. The climate envelopes of all applicable species in the assemblage are overlapped to find the mutual intersection of the climatic ranges. This provides a quantitative measure of the palaeoclimate at the time of the assemblage deposition (Atkinson et. al., 1987). While providing a quantitative measure of temperature MCR has been found to underestimate maximum temperatures (TMAX) and overestimate minimum temperatures (TMIN) in extremely cold environments. TMIN can also be underestimated in areas with milder winters (Lowe & Walker, 1997). However these errors can be corrected for using regression equations. Currently these equations have been calibrated for Europe (Atkinson et. al. 1987) and North American sites (Elias, 1997; Elias et. al., 1999).




Herbivorous beetle species, while generally excluded from MCR analysis due to their potential relationship to host-plants, are extremely useful in palaeoenvironmental reconstruction. Some phytophagous beetle species, such as some scolytids (bark beetles) (Morgan & Morgan, 1980), are restricted in their distribution to certain species of trees. When discovered in a fossil assemblage these beetle species therefore indicate that the required host-plant was present at the study site at the time of deposition. The application of phytophagus beetle fossils for this purpose is possible in a New Zealand context as previously shown by Marra (2002, 2003).


It should be noted that MCR requires an extremely detailed knowledge of beetle distributions and environmental tolerances to be accurate. New Zealand when compared is sadly lacking in this data when compared to the extensive datasets of such information available in the Northern Hemisphere. However further work by Marra et. al. (2004) has produced a statistical method of establishing quantitative measures of palaeoclimate. This method, the Maximum Likelihood Estimate (MLE), is specifically designed to deal with the smaller datasets available in New Zealand.




其實我的專長是古代生物學



總結在下面,有點長



T:  Beetle Fossil for palaeoclimatic
S:  Explain
A:  Oppose Pollen/Plan, Support Beetle Fossil

• Why Beetle Fossil is excellent indicator for palaeoenvironment
  
  1. Preserved as disarticulated skeletal fragments in organic sediments
     
     1. => preserved well
        
     2. => structure detail can be distinguished
        
  2. Has great degree of morphological constancy for at least 1.64M years
     
     1. Include genitalia, used in the identification of taxa
        
     2. Physiology requirements of beetles have also remained the same
        
  3. Evidence supported assumption:
     
     1. Composition of beetle communities has remain relative constant
        
     2. Host-specific phytophagous  species can be sometimes be found in association with the macrofossils of their host plant
        
  4. the ectothermic nature of beetles -> reliance on environmental conditions
     
• Why Beetle Fossil is better than Pollen fossil
  
  1. Pro for Beetle
     
     1. Beetle is more diverse (eg, desert, rainforest, littoral)
        
     2. Beetle and inset respond more rapidly to climate change by  dispersal, rather than speciation
        
     3. generally identifiable to species level
        
  2. Cons for Pollen
     
     1. some genera of plants contain species with different ecological requirements, but with indistinguishable pollen
        
  3. Bettle vs Pollen
     
     1. predatory and scavenging beetle species are able to take advantage of recently modified areas (along with pioneer plant species) before the trees and shrubs with similar climatic requirements.
        
     2. =>Trees and shrubs can therefore lag behind the actual period of climatic change and the resultant spread of beetles.
        
     3. => revealed short-term climate fluctuations that are not observed in the pollen record .
        
     4. Beetles fossils also avoid the problem of contamination of the local pollen rain (and hence local climate signal) by long-distance wind dispersed pollen such as that of Nothofagus
        
• 3) How to use Beetle Fossil –
  
  • by Mutual Climatic Range(MCR)
    
    • MCR uses the modern distribution of a species found within a fossil beetle assemblage to construct a climate envelope for that species
      
    • based on the observation that the contemporary distribution of a beetle species is seen to measure its climatic tolerances
      
    • host plant does not respond climate change quickly => herbivorous species is limited by host-plant => only use predatory/scavenging beetle
      
  • by Herbivorous beetle species,  useful in palaeoenvironmental reconstruction
    
    • ex: bark beetles  are restricted in their distribution to certain species of trees
      
    • Found the H  beetle fossil => the required host-plant was present at the study site at the time of deposition
      

再來幾題裸機


1) LZ 前帖說是做Finance,這帖又說專長是古代生物學
问：解释原因

2) LZ 前帖說是做Finance,這帖又說專長是古代生物學 結論 LZ說謊
问：支持


3) LZ 前帖說是做Finance,這帖又說專長是古代生物學 結論 LZ在考古公司做財務的
问：假设

4) LZ 前帖說是做Finance,這帖又說專長是古代生物學 結論 LZ修了雙學位

问：削弱

zxfjacob

童鞋~~弱弱地问一下，你的原文资料都是怎么搜索到的啊？？

海砂516

。。。。这牛人辈出啊!!!!

sparklelynn

哎呦~~~每次给雪菲惊喜的LZ又来了


雪菲只会做一道哦~~

3) LZ 前帖說是做Finance,這帖又說專長是古代生物學結論 LZ在考古公司做財務的
问：假设
真有考古介样滴公司，噗~~ o(*￣▽￣*)o

kyky

谢谢楼主

爆炒拖鞋

adidas0029

thx

juijui1234

楼主厉害！

candicelll

thx

xohe赵

NB啊