生物工程专业英语文档格式.docx
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advantage
standard
ofreproductive
isolation
that
it
very
precise.
Notice,
however,
only
be
applied
organismsthat
reproduce
sexually.
Asexual
reproducers,
including
most
prokaryotes,
many
plants,
and
someanimals,
must
classified
into
on
basis
physical
(biochemical
morphological)
traits.
现代生物学大体将物种定义为实际上的一群或潜在的杂交群体,即从这个群体隔离繁殖的后代。
种族中个体可以互相交配,但种间不能。
这种繁殖隔离的一个优势是很精确。
但仅适用于性繁殖的生物。
非性繁殖,包括大多数原核生物,许多植物,某些动物,需要通过自然特征进行归类。
2.Preventing
Gene
Exchange
Two
general
types
mechanisms
operate
block
exchange
genes
between
individuals
relatedgroups.
first
type
made
up
prezygotic
isolating
prevent
formation
ofzygotes.
Prezygotic
falls
two
categories:
ecological
behavioral.
In
case,
tworelated
may
become
adapted
slightly
different
environments-perhaps
varying
soil
foodsources.
Over
time,
these
genetic
differences
so
great
successful
cross-fertilization
nolonger
take
place.
behavioral
isolation,
related
groups
evolve
differing
behaviors
specificmating
rituals-that
restrict
members
same
group.
两种基因型机制阻碍了相关群体中个体的基因交换。
第一种基因型由前合子机械隔离机制阻止合子的生成。
前合子隔离分两类:
生态学的和行为学的。
第一种情况,两个相关群体可能分别适应稍微不同的环境,如土壤类型或食物来源的变化。
长时间,这些遗传差异变得很大而很难异体受精。
而行为学隔离,相关的群组进化成不同的行为方式,例如,结婚仪式,从而限制了同群成员基因交流。
Sometimes
produce
involve
mechanical
isolation.
That
is,mating
physically
impossible
because
genitals
males
andfemales
are
structurally
incompatible
molecules
surfaces
sperm
egg
fail
bind.A
final
mechanism
temporal
in
which
time-related
environmental
cues
thattrigger
reproductive
processes
for
species.
有时,产生前合子隔离的差异涉及了隔离机制。
即,由于生殖器结构不匹配或精卵分子表面不结合而使不同种群成员间不能自然结合。
最后一类前合子机制是暂时隔离,与时间有关的环境因素触发了相关物种的不同繁殖过程。
postzygotic
mating
occur,
but
resulting
hybrid
organism
inviable
orsterile.
special
case
sterility
termed
breakdown,
second
subsequentgenerations
after
cross
show
reduced
success.
Contrast
this
fact
differentoutcome
crossbreeding
genetically
distant
species,
where
result
isoften
heterozygote
(hybrid
vigor).
在合子后隔离机制中,匹配可以进行,但或不产生杂种或杂种不育。
杂种不育在某些特殊情况下,是指第二代或以后几代显示出杂交繁殖能力的降低。
正是同种远基因成员间的杂交产生不同的结果,而产生杂种优势。
Populations
spread
out
over
broad
geographical
range
often
arrayed
cline-a
gradual
change
one
more
characteristics
population
evolves
adaptations
its
own
localenvironment.
Along
cline,
subspecies
distinct
arise.
Often,
at
eitherend
cline
isolated.
地域上分布很广的种的群体中,经常存在变异群,因为适应当地的环境,每个群体逐渐产生一个或多个与众不同的特点。
在变异群中,带有明显特征的亚群可能产生。
通常,在两个变异群中的个体是繁殖隔离的。
3.Becoming
Species:
How
Pools
Become
Isolated
Ernst
Mayr'
s
model
allopatric
speciation
proposes
originate
two-stage
process.In
stage,
populations
existing
separated
by
barrier.
As
aresult,
time
leading
pre-
arise
groups.In
diverged
again
come
contact.
If
happens,
speciationbecomes
complete
through
action
natural
selection.
Lesson
Nine
is,
28
One
selection
异地物种形成模型认为,物种可能起源于两个阶段。
第一阶段,已经存在的物种群体可能由于自然或地理屏障被隔离。
结果,长时间后,在两个群体间遗传差异导致前合子或后合子隔离的产生。
第二阶段,这些趋异群体可能再次接触,物种发生可能通过自然选择发生。
4.The
Genetic
Bases
speciation
extent
diverging
separate
betweenspecies
have
already
represented
statistic
called
identity-the
relativeproportion
structural
present
being
compared.
general,biologists
believe
events
place
gradually.
Once
new
specieshas
arisen,
tends
diverge
rapid
pace.
some
cases,
asthe
primate
order,
major
body
form
not
reflected
corresponding
divergences
instructural
genes.
This
has
led
hypothesize
small
changes
regulatory
mayaccount
large-scale
responsible
sepciation
origin
higher
taxonomicgroups.
能够趋异的群体或已经趋异的物种,他们之间差异的扩大,由一个稳定的遗传识别代表。
即在可比群体成员中相同基因所占相关比例。
大体而言,生物学家相信,遗传导致的物种形成是逐渐发生的。
在某些情况下,身体主要差别并不能反映结构基因的趋异,生物学家因此提出,调控基因很少的改变可能导致很大规模物种改变和更高分类学上群体的产生。
rapidly
split
polyploidization—the
suddenmultiplication
an
entire
complement
chromosomes.
sympatric
speciation,
whichnew
even
though
no
taken
A
phenomenon
similar
topolyploidization
involving
rearrangement
chromosomes
been
proposed
explain
theevolutionary
giant
pandas.
Clearly,
variety
ways.
遗传学上可以快速分离群体的一个机制是多倍体,一个完全互补染色体组的突然倍增。
结果导致同域物种形成,即使没有地理隔离也会产生新的物种。
与多倍体相似的一个现象是染色体重排,可以解释巨大熊猫的进化起源。
显然,物种可以以多种方式进化。
5.Explaining
Macroevolution:
Higher-order
Changes
generate
sometimes
microevolution;
those
majorphenotypic
genera,
classes,
orders,
macroevolution.
Somelines
descent
traced
studying
fossil
record.
other
cases
relationships
inferredby
comparison
living
organisms.
When
lines
evolutionary
constructed,the
phylogeny.
遗传物种的改变有时称微进化;
那些产生很大差异用来区分属,纲,目的表型变化称大幅进化